Author: "Antonia Rowlinson" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Antonia Rowlinson"' showing total 90 results

Start Over Author "Antonia Rowlinson"

90 results on '"Antonia Rowlinson"'

1. A Radio Flare in the Long-lived Afterglow of the Distant Short GRB 210726A: Energy Injection or a Reverse Shock from Shell Collisions?

Author: Genevieve Schroeder, Lauren Rhodes, Tanmoy Laskar, Anya Nugent, Alicia Rouco Escorial, Jillian C. Rastinejad, Wen-fai Fong, Alexander J. van der Horst, Péter Veres, Kate D. Alexander, Alex Andersson, Edo Berger, Peter K. Blanchard, Sarah Chastain, Lise Christensen, Rob Fender, David A. Green, Paul Groot, Ian Heywood, Assaf Horesh, Luca Izzo, Charles D. Kilpatrick, Elmar Körding, Amy Lien, Daniele B. Malesani, Vanessa McBride, Kunal Mooley, Antonia Rowlinson, Huei Sears, Ben Stappers, Nial Tanvir, Susanna D. Vergani, Ralph A. M. J. Wijers, David Williams-Baldwin, and Patrick Woudt
Subjects: Gamma-ray bursts, High energy astrophysics, Radio astronomy, Time domain astronomy, Astrophysics, QB460-466
Abstract: We present the discovery of the radio afterglow of the short gamma-ray burst (GRB) 210726A, localized to a galaxy at a photometric redshift of z ∼ 2.4. While radio observations commenced ≲1 day after the burst, no radio emission was detected until ∼11 days. The radio afterglow subsequently brightened by a factor of ∼3 in the span of a week, followed by a rapid decay (a “radio flare”). We find that a forward shock afterglow model cannot self-consistently describe the multiwavelength X-ray and radio data, and underpredicts the flux of the radio flare by a factor of ≈5. We find that the addition of substantial energy injection, which increases the isotropic kinetic energy of the burst by a factor of ≈4, or a reverse shock from a shell collision are viable solutions to match the broadband behavior. At z ∼ 2.4, GRB 210726A is among the highest-redshift short GRBs discovered to date, as well as the most luminous in radio and X-rays. Combining and comparing all previous radio afterglow observations of short GRBs, we find that the majority of published radio searches conclude by ≲10 days after the burst, potentially missing these late-rising, luminous radio afterglows.
Published: 2024
Full Text: View/download PDF

2. Low-frequency radio observations of recurrent nova RS Ophiuchi with MeerKAT and LOFAR

Author: Iris de Ruiter, Miriam M Nyamai, Antonia Rowlinson, Ralph A M J Wijers, Tim J O’Brien, David R A Williams, and Patrick Woudt
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: We report low-frequency radio observations of the 2021 outburst of the recurrent nova RS Ophiuchi. These observations include the lowest frequency observations of this system to date. Detailed light curves are obtained by MeerKAT at 0.82 and 1.28 GHz and LOFAR at 54 and 154 MHz. These low-frequency detections allow us to put stringent constraints on the brightness temperature that clearly favour a non-thermal emission mechanism. The radio emission is interpreted and modelled as synchrotron emission from the shock interaction between the nova ejecta and the circumbinary medium. The light curve shows a plateauing behaviour after the first peak, which can be explained by either a non-uniform density of the circumbinary medium or a second emission component. Allowing for a second component in the light curve modelling captures the steep decay at late times. Furthermore, extrapolating this model to 15 years after the outburst shows that the radio emission might not fully disappear between outbursts. Further modelling of the light curves indicates a red giant mass loss rate of $\sim 5 \cdot 10^{-8}~{\rm M_\odot~yr^{-1}}$. The spectrum cannot be modelled in detail at this stage, as there are likely at least four emission components. Radio emission from stellar wind or synchrotron jets are ruled out as the possible origin of the radio emission. Finally, we suggest a strategy for future observations that would advance our understanding of the physical properties of RS Oph., submitted to MNRAS
Published: 2023

3. Limits on long-time-scale radio transients at 150 MHz using the TGSS ADR1 and LoTSS DR2 catalogues

Author: Iris de Ruiter, Guillaume Leseigneur, Antonia Rowlinson, Huib Intema, Timothy W. Shimwell, Ralph A. M. J. Wijers, A. Drabent, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Radio Continuum, media_common.quotation_subject, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Scale (descriptive set theory), LOFAR, Astrophysics, Catalogues, Transients, Compact space, Space and Planetary Science, Sky, Cutoff, Limit (mathematics), Transient (oscillation), General, Astrophysics - High Energy Astrophysical Phenomena, media_common
Abstract: We present a search for transient radio sources on timescales of 2 to 9 yr at 150 MHz. This search is conducted by comparing the first Alternative Data Release of the TIFR GMRT Sky Survey (TGSS ADR1) and the second data release of the LOFAR Two-metre Sky Survey (LoTSS DR2). The overlapping survey area covers 5570 $\rm{deg}^2$ on the sky, or 14 per cent of the total sky. We introduce a method to compare the source catalogues that involves a pair match of sources, a flux density cutoff to meet the survey completeness limit and a newly developed compactness criterion. This method is used to identify both transient candidates in the TGSS source catalogue that have no counterpart in the LoTSS catalogue and transient candidates in LoTSS without a counterpart in TGSS. We find that imaging artefacts and uncertainties and variations in the flux density scales complicate the transient search. Our method to search for transients by comparing two different surveys, while taking into account imaging artefacts around bright sources and misaligned flux scales between surveys, is universally applicable to future radio transient searches. No transient sources were identified, but we are able to place an upper limit on the transient surface density of $, 14 pages, 11 figures
Published: 2021

4. LOFAR early-time search for coherent radio emission from short GRB 181123B

Author: A. J. van der Horst, Ralph A. M. J. Wijers, Antonia Rowlinson, S. ter Veen, G. E. Anderson, R. L. C. Starling, K. Gourdji, Timothy W. Shimwell, S. Mandhai, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Phase (waves), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, LOFAR, Astrophysics::Cosmology and Extragalactic Astrophysics, Electromagnetic emission, Kilonova, 01 natural sciences, Black hole, Neutron star, Space and Planetary Science, 0103 physical sciences, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Short duration, Astrophysics::Galaxy Astrophysics
Abstract: The mergers of two neutron stars are typically accompanied by broad-band electromagnetic emission from either a relativistic jet or a kilonova. It has also been long predicted that coherent radio emission will occur during the merger phase or from a newly formed neutron star remnant, however this emission has not been seen to date. This paper presents the deepest limits for this emission from a neutron star merger folowing triggered LOFAR observations of the short gamma-ray burst (SGRB) 181123B, starting 4.4 minutes after the GRB occurred. During the X-ray plateau phase, a signature of ongoing energy injection, we detect no radio emission to a 3$\sigma$ limit of 153 mJy at 144 MHz (image integration time of 136 seconds), which is significantly fainter than the predicted emission from a standard neutron star. At a redshift of 1.8, this corresponds to a luminosity of $2.5 \times 10^{44}$ erg s$^{-1}$. Snapshot images were made of the radio observation on a range of timescales, targeting short duration radio flashes similar to fast radio bursts (FRBs). No emission was detected in the snapshot images at the location of GRB 181123B enabling constraints to be placed on the prompt coherent radio emission model and emission predicted to occur when a neutron star collapses to form a black hole. At the putative host redshift of 1.8 for GRB 181123B, the non detection of the prompt radio emission is two orders of magnitude lower than expected for magnetic reconnection models for prompt GRB emission and no magnetar emission is expected., Comment: MNRAS Accepted, 11 pages, 6 figures
Published: 2021

5. Apparent radio transients mapping the near-Earth plasma environment

Author: Antonia Rowlinson, Ralph A. M. J. Wijers, Aleksandar Shulevski, Mark Kuiack, High Energy Astrophys. & Astropart. Phys (API, FNWI), and API Other Research (FNWI)
Subjects: Electron density, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, 01 natural sciences, Altitude, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Toy model, Astronomy, Astronomy and Astrophysics, Plasma, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Ionosphere, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Event (particle physics), Astrophysics - Earth and Planetary Astrophysics
Abstract: We report the discovery of bright, fast, radio flashes lasting tens of seconds with the AARTFAAC high-cadence all-sky survey at 60 MHz. The vast majority of these coincide with known, bright radio sources that brighten by factors of up to 100 during such an event. We attribute them to magnification events induced by plasma near the Earth, most likely in the densest parts of the ionosphere. They can occur both in relative isolation, during otherwise quiescent ionospheric conditions, and in large clusters during more turbulent ionospheric conditions. Using a toy model, we show that the likely origin of the more extreme (up to a factor of 100 or so) magnification events likely originate in the region of peak electron density in the ionosphere, at an altitude of 300-400 km. Distinguishing these events from genuine astrophysical transients is imperative for future surveys searching for low frequency radio transient at timescales below a minute., 11 pages, 10 figures. Accepted by MNRAS
Published: 2021

6. Rapid-response radio observations of short GRB 181123B with the Australia Telescope Compact Array

Author: Antonia Rowlinson, Jamie Stevens, Richard M. Plotkin, Ralph A. M. J. Wijers, G. E. Anderson, Jean-Pierre Macquart, Paul Hancock, M. D. Aksulu, James Miller-Jones, Martin Bell, Arash Bahramian, A. J. van der Horst, Stuart D. Ryder, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gravitational wave, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, Electron, Radio spectrum, LIGO, Afterglow, law.invention, Telescope, Space and Planetary Science, law, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst
Abstract: We introduce the Australia Telescope Compact Array (ATCA) rapid-response mode by presenting the first successful trigger on the short-duration gamma-ray burst (GRB) 181123B. Early-time radio observations of short GRBs may provide vital insights into the radio afterglow properties of Advanced LIGO- and Virgo-detected gravitational wave events, which will in turn inform follow-up strategies to search for counterparts within their large positional uncertainties. The ATCA was on target within 12.6 hr post-burst, when the source had risen above the horizon. While no radio afterglow was detected during the 8.3 hr observation, we obtained force-fitted flux densities of $7 \pm 12$ and $15 \pm 11~\mu$Jy at 5.5 and 9 GHz, respectively. Afterglow modelling of GRB 181123B showed that the addition of the ATCA force-fitted radio flux densities to the Swift X-ray Telescope detections provided more stringent constraints on the fraction of thermal energy in the electrons (log$\epsilon_e = -0.75^{+0.39}_{-0.40}$ rather than log$\epsilon_e = -1.13^{+0.82}_{-1.2}$ derived without the inclusion of the ATCA values), which is consistent with the range of typical $\epsilon_e$ derived from GRB afterglow modelling. This allowed us to predict that the forward shock may have peaked in the radio band $\sim10$ days post-burst, producing detectable radio emission $\gtrsim3-4$ days post-burst. Overall, we demonstrate the potential for extremely rapid radio follow-up of transients and the importance of triggered radio observations for constraining GRB blast wave properties, regardless of whether there is a detection, via the inclusion of force-fitted radio flux densities in afterglow modelling efforts., Comment: 15 pages, 7 figures, accepted for publication in MNRAS
Published: 2021

7. The AARTFAAC Cosmic Explorer

Author: Michiel A. Brentjens, Sarod Yatawatta, Ralph A. M. J. Wijers, A. M. Sardarabadi, Maaijke Mevius, Saleem Zaroubi, Antonia Rowlinson, Luitje Koopmans, A. R. Offringa, Mark Kuiack, B. K. Gehlot, Vishambhar Pandey, Florent Mertens, Aleksandar Shulevski, Harish Vedantham, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), High Energy Astrophys. & Astropart. Phys (API, FNWI), Astronomy, and Kapteyn Astronomical Institute
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), first stars, FOS: Physical sciences, Astrophysics, 01 natural sciences, Spectral line, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Absorption (logic), dark ages, 010306 general physics, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, methods: statistical, Degree (graph theory), Spectral density, Astronomy and Astrophysics, methods: data analysis, Redshift, diffuse radiation, techniques: interferometric, Space and Planetary Science, Dark Ages, reionization, radio lines: general, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted by traditional astrophysical models. If genuine, a deeper absorption may lead to stronger fluctuations on the 21-cm signal on degree scales (up to 1~Kelvin in rms), allowing these fluctuations to be detectable in nearly 50~times shorter integration times compared to previous predictions. We commenced the "AARTFAAC Cosmic Explorer" (ACE) program, that employs the AARTFAAC wide-field imager, to measure or set limits on the power spectrum of the 21-cm fluctuations in the redshift range $z = 17.9-18.6$ ($\Delta\nu = 72.36-75.09$~MHz) corresponding to the deep part of the EDGES absorption feature. Here, we present first results from two LST bins: 23.5-23.75h and 23.5-23.75h, each with 2~h of data, recorded in `semi drift-scan' mode. We demonstrate the application of the new ACE data-processing pipeline (adapted from the LOFAR-EoR pipeline) on the AARTFAAC data. We observe that noise estimates from the channel and time-differenced Stokes~$V$ visibilities agree with each other. After 2~h of integration and subtraction of bright foregrounds, we obtain $2\sigma$ upper limits on the 21-cm power spectrum of $\Delta_{21}^2 < (8139~\textrm{mK})^2$ and $\Delta_{21}^2 < (8549~\textrm{mK})^2$ at $k = 0.144~h\,\textrm{cMpc}^{-1}$ for the two LST bins. Incoherently averaging the noise bias-corrected power spectra for the two LST bins yields an upper limit of $\Delta_{21}^2 < (7388~\textrm{mK})^2$ at $k = 0.144~h\,\textrm{cMpc}^{-1}$. These are the deepest upper limits thus far at these redshifts., Comment: 16 pages, 10 figures, accepted for publication in MNRAS
Published: 2020

8. LOFAR detectability of prompt low-frequency radio emission during gamma-ray burst X-ray flares

Author: Ralph A. M. J. Wijers, Antonia Rowlinson, R. L. C. Starling, A. J. van der Horst, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, Astronomy and Astrophysics, LOFAR, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, Radiation, Light curve, law.invention, Stars, Space and Planetary Science, law, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Gamma-ray burst, Instrumentation and Methods for Astrophysics (astro-ph.IM), Flare
Abstract: The prompt emission in long gamma-ray bursts arises from within relativistic outflows created during the collapse of massive stars, and the mechanism by which radiation is produced may be either magnetically- or matter-dominated. In this work we suggest an observational test of a magnetically-dominated Poynting flux model that predicts both gamma-ray and low-frequency radio pulses. A common feature among early light curves of long gamma-ray bursts are X-ray flares, which have been shown to arise from sites internal to the jet. Ascribing these events to the prompt emission, we take an established Swift XRT flare sample and apply a magnetically-dominated wind model to make predictions for the timing and flux density of corresponding radio pulses in the ~100-200 MHz band observable with radio facilities such as LOFAR. We find that 44 per cent of the X-ray flares studied would have had detectable radio emission under this model, for typical sensitivities reached using LOFAR's rapid response mode and assuming negligible absorption and scattering effects in the interstellar and intergalactic medium. We estimate the rate of Swift gamma-ray bursts displaying X-ray flares with detectable radio pulses, accessible to LOFAR, of order seven per year. We determine that LOFAR triggered observations can play a key role in establishing the long debated mechanism responsible for gamma-ray burst prompt emission., Comment: 7 pages, 4 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
Published: 2020

9. Searching for low radio-frequency gravitational wave counterparts in wide-field LOFAR data

Author: J. W. Broderick, Aleksandar Shulevski, Antonia Rowlinson, K. Gourdji, Peter G. Jonker, Ralph A. M. J. Wijers, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Field (physics), Gravitational wave, black hole - neutron star mergers, Astronomy, Binary number, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, LOFAR, Compact star, radio continuum transients, Neutron star, gravitational waves, Space and Planetary Science, techniques interferometric, neutron star mergers, Neutron, Radio frequency, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The electromagnetic counterparts to gravitational wave (GW) merger events are highly sought after, but difficult to find owing to large localization regions. In this study, we present a strategy to search for compact object merger radio counterparts in wide-field data collected by the Low-Frequency Array (LOFAR). In particular, we use multi-epoch LOFAR observations centred at 144 MHz spanning roughly 300 deg$^2$ at optimum sensitivity of a since retracted neutron star-black hole merger candidate detected during O2, the second Advanced Ligo-Virgo GW observing run. The minimum sensitivity of the entire (overlapping) 1809 deg$^2$ field searched is 50 mJy and the false negative rate is 0.1 per cent above 200 mJy. We do not find any transients and thus place an upper limit at 95 per cent confidence of 0.02 transients per square degree above 20 mJy on one, two and three month timescales, which are the most sensitive limits available to date. Finally, we discuss the prospects of observing GW events with LOFAR in the upcoming GW observing run and show that a single multi-beam LOFAR observation can probe the full projected median localization area of binary neutron star mergers down to a median sensitivity of at least 8 mJy., Comment: Accepted version (in MNRAS)
Published: 2022

10. Detecting dispersed radio transients in real time using convolutional neural networks

Author: Ralph A. M. J. Wijers, David Ruhe, Patrick Forré, Antonia Rowlinson, Mark Kuiack, Amsterdam Machine Learning lab (IVI, FNWI), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Data stream, Measure (data warehouse), Computer science, Pipeline (computing), Real-time computing, FOS: Physical sciences, Inference, Astronomy and Astrophysics, LOFAR, Convolutional neural network, Computer Science Applications, Image (mathematics), Space and Planetary Science, Transient (computer programming), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: We present a methodology for automated real-time analysis of a radio image data stream with the goal to find transient sources. Contrary to previous works, the transients we are interested in occur on a time-scale where dispersion starts to play a role, so we must search a higher-dimensional data space and yet work fast enough to keep up with the data stream in real time. The approach consists of five main steps: quality control, source detection, association, flux measurement, and physical parameter inference. We present parallelized methods based on convolutions and filters that can be accelerated on a GPU, allowing the pipeline to run in real-time. In the parameter inference step, we apply a convolutional neural network to dynamic spectra that were obtained from the preceding steps. It infers physical parameters, among which the dispersion measure of the transient candidate. Based on critical values of these parameters, an alert can be sent out and data will be saved for further investigation. Experimentally, the pipeline is applied to simulated data and images from AARTFAAC (Amsterdam Astron Radio Transients Facility And Analysis Centre), a transients facility based on the Low-Frequency Array (LOFAR). Results on simulated data show the efficacy of the pipeline, and from real data it discovered dispersed pulses. The current work targets transients on time scales that are longer than the fast transients of beam-formed search, but shorter than slow transients in which dispersion matters less. This fills a methodological gap that is relevant for the upcoming Square-Kilometer Array (SKA). Additionally, since real-time analysis can be performed, only data with promising detections can be saved to disk, providing a solution to the big-data problem that modern astronomy is dealing with.
Published: 2022

11. Sub-arcsecond imaging with the International LOFAR Telescope II. Completion of the LOFAR Long-Baseline Calibrator Survey

Author: G. K. Miley, Annalisa Bonafede, M. P. van Haarlem, Jochen Eislöffel, John McKean, P. C. G. van Dijk, M. A. Garrett, B. Ciardi, R. Blaauw, E. Jütte, Harvey Butcher, O. Wucknitz, Luitje Koopmans, Oleg Smirnov, M. Pandey-Pommier, Pietro Zucca, Joseph R. Callingham, S. Mooney, R. J. van Weeren, A. Nelles, Antonia Rowlinson, W. Reich, Heino Falcke, S. Duscha, Rajan Chhetri, Emanuela Orrú, G. Mann, Dominik J. Schwarz, Michiel A. Brentjens, P. Zarka, M. Ruiter, Hanna Rothkaehl, Kaspars Prūsis, Ralph A. M. J. Wijers, S. Badole, Jean-Mathias Griessmeier, P. Maat, Neal Jackson, Marco Iacobelli, Jeremy J. Harwood, Andrzej Krankowski, M. J. Norden, Vishambhar Pandey, A. J. van der Horst, John Morgan, F. Sweijen, Adam Deller, George Heald, S. Damstra, Martin J. Hardcastle, Mark J. Bentum, Ashish Asgekar, Leah K. Morabito, A. W. Gunst, M. Tagger, A. Shulevski, C. Vocks, A. Drabent, Javier Moldon, A. H. W. M. Coolen, M. Paas, Atvars Nikolajevs, W. N. Brouw, J. Sluman, Roberto Pizzo, Marcus Brüggen, Henk Mulder, Matthias Hoeft, F. de Gasperin, I. M. Avruch, J. A. Zensus, Arthur Corstanje, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), European Commission, Ministerio de Ciencia e Innovación (España), Netherlands Organization for Scientific Research, UK Research and Innovation, Chinese Academy of Sciences, High Energy Astrophys. & Astropart. Phys (API, FNWI), Kapteyn Astronomical Institute, Center for Wireless Technology Eindhoven, and EM for Radio Science Lab
Subjects: active -Radio continuum, active [Galaxies], Radio galaxy, galaxies -Atmospheric physics, Astronomy, media_common.quotation_subject, FOS: Physical sciences, Flux, Murchison Widefield Array, ionosphere, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Surveys, Interplanetary scintillation, Instrumentation and Methods for Astrophysics (astro-ph.IM), Instrumentation, Remote sensing, media_common, Physics, Spectral index, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Radio lines: galaxies, Astrophysics::Instrumentation and Methods for Astrophysics, interferometers [Instrumentation], Astronomy and Astrophysics, Quasar, LOFAR, Galaxies: active, interferometers -Techniques, Astrophysics - Astrophysics of Galaxies, galaxies [Radio lines], Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], Instrumentation: interferometers, Astrophysics of Galaxies (astro-ph.GA), Techniques: interferometric, interferometric [Techniques], interferometric -Surveys -Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Full list of authors: Jackson, N.; Badole, S.; Morgan, J.; Chhetri, R.; Prūsis, K.; Nikolajevs, A.; Morabito, L.; Brentjens, M.; Sweijen, F.; Iacobelli, M.; Orrù, E.; Sluman, J.; Blaauw, R.; Mulder, H.; van Dijk, P.; Mooney, S.; Deller, A.; Moldon, J.; Callingham, J. R.; Harwood, J.; Hardcastle, M.; Heald, G.; Drabent, A.; McKean, J. P.; Asgekar, A.; Avruch, I. M.; Bentum, M. J.; Bonafede, A.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Coolen, A.; Corstanje, A.; Damstra, S.; Duscha, S.; Eislöffel, J.; Falcke, H.; Garrett, M.; de Gasperin, F.; Griessmeier, J. -M.; Gunst, A. W.; van Haarlem, M. P.; Hoeft, M.; van der Horst, A. J.; Jütte, E.; Koopmans, L. V. E.; Krankowski, A.; Maat, P.; Mann, G.; Miley, G. K.; Nelles, A.; Norden, M.; Paas, M.; Pandey, V. N.; Pandey-Pommier, M.; Pizzo, R. F.; Reich, W.; Rothkaehl, H.; Rowlinson, A.; Ruiter, M.; Shulevski, A.; Schwarz, D. J.; Smirnov, O.; Tagger, M.; Vocks, C.; van Weeren, R. J.; Wijers, R.; Wucknitz, O.; Zarka, P.; Zensus, J. A.; Zucca, P., The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper, we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30 006 observations of 24 713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of ≥200 km baselines is identified by the detection of compact flux density, for declinations north of 30° and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. The catalogue contains indicators of degree of correlated flux on baselines between the Dutch core and each of the international stations, involving a maximum baseline length of nearly 2000 km, for all of the observations. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2′′, for sources observed in the survey. The survey is used to estimate the phase coherence time of the ionosphere for the LOFAR international baselines, with median phase coherence times of about 2 min varying by a few tens of percent between theshortest and longest baselines. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2′′ and 300 mas. The LBCS survey sources show a greater incidence of compact flux density in quasars than in radio galaxies, consistent with unified schemes of radio sources. Comparison with samples of sources from interplanetary scintillation (IPS) studies with the Murchison Widefield Array shows consistent patterns of detection of compact structure in sources observed both interferometrically with LOFAR and using IPS. © ESO 2022., Support for the operation of the MWA is provided by the Australian Government (NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. We acknowledge the Pawsey Supercomputing Centre which is supported by the Western Australian and Australian Governments. A.D. acknowledges support by the BMBF Verbundforschung under the grant 052020. L.K.M. is grateful for support from the UKRI Future Leaders Fellowship (grant MR/T042842/1). J. Moldón acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) and from the grant RTI2018-096228-B-C31 (MICIU/FEDER, EU). J.P.M. acknowledges support from the Netherlands Organization for Scientific Research (NWO, project number 629.001.023) and the Chinese Academy of Sciences (CAS, project number 114A11KYSB20170054).
Published: 2022

12. Strong low-frequency radio flaring from Cygnus X-3 observed with LOFAR

Author: Guy G. Pooley, Antonia Rowlinson, N. N. Bursov, N. A. Nizhelskij, Rob Fender, J. W. Broderick, David R. Williams, A. V. Shevchenko, Jai Verdhan Chauhan, Joe Bright, S. A. Trushkin, David A. Green, Stephane Corbel, P. G. Tsybulev, Thomas D. Russell, High Energy Astrophys. & Astropart. Phys (API, FNWI), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Green, David [0000-0003-3189-9998], Apollo - University of Cambridge Repository, Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Arcminute Microkelvin Imager, FOS: Physical sciences, Astrophysics, Low frequency, 01 natural sciences, Radio spectrum, law.invention, Telescope, X-rays: binaries, law, 0103 physical sciences, 010303 astronomy & astrophysics, stars [radio continuum], High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, 010308 nuclear & particles physics, jets and outflows [ISM], Astronomy and Astrophysics, LOFAR, Light curve, ISM: jets and outflows, Space and Planetary Science, individual: Cygnus X-3 [stars], stars: individual: Cygnus X-3, binaries [X-rays], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, radio continuum: stars, Flare
Abstract: We present Low-Frequency Array (LOFAR) 143.5-MHz radio observations of flaring activity during 2019 May from the X-ray binary Cygnus X-3. Similar to radio observations of previous outbursts from Cygnus X-3, we find that this source was significantly variable at low frequencies, reaching a maximum flux density of about 5.8 Jy. We compare our LOFAR light curve with contemporaneous observations taken at 1.25 and 2.3 GHz with the RATAN-600 telescope, and at 15 GHz with the Arcminute Microkelvin Imager (AMI) Large Array. The initial 143.5-MHz flux density level, $\sim$2 Jy, is suggested to be the delayed and possibly blended emission from at least some of the flaring activity that had been detected at higher frequencies before our LOFAR observations had begun. There is also evidence of a delay of more than four days between a bright flare that initially peaked on May 6 at 2.3 and 15 GHz, and the corresponding peak ($\gtrsim$ 5.8 Jy) at 143.5 MHz. From the multi-frequency light curves, we estimate the minimum energy and magnetic field required to produce this flare to be roughly 10$^{44}$ erg and 40 mG, respectively, corresponding to a minimum mean power of $\sim$10$^{38}$ erg s$^{-1}$. Additionally, we show that the broadband radio spectrum evolved over the course of our observing campaign; in particular, the two-point spectral index between 143.5 MHz and 1.25 GHz transitioned from being optically thick to optically thin as the flare simultaneously brightened at 143.5 MHz and faded at GHz frequencies., 14 pages, 6 figures, 4 tables, accepted for publication in MNRAS
Published: 2021

13. The Murchison Widefield Array Transients Survey (MWATS)

Author: John Morgan, Sarah V. White, Rachel L. Webster, Steven Tingay, Gianni Bernardi, David L. Kaplan, Miguel F. Morales, Joseph R. Callingham, Stephen M. Ord, Philip G. Edwards, Natasha Hurley-Walker, Antonia Rowlinson, Christopher L. Williams, D. Oberoi, Colin J. Lonsdale, F. Briggs, E. Morgan, Richard W. Hunstead, Martin Bell, Daniel A. Mitchell, N. Udaya Shankar, Bryna J. Hazelton, Bryan Gaensler, A. R. Offringa, Melanie Johnston-Hollitt, K. S. Srivani, Simon Johnston, Thiagaraj Prabu, Rajan Chhetri, Randall B. Wayth, Judd D. Bowman, Elaine M. Sadler, Lincoln J. Greenhill, Andrew Williams, Paul Hancock, Avinash A. Deshpande, Ravi Subrahmanyan, Tara Murphy, Steve Croft, Stephen R. McWhirter, Roger J. Cappallo, ITA, USA, AUS, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Astronomy
Subjects: 010504 meteorology & atmospheric sciences, media_common.quotation_subject, FOS: Physical sciences, Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Stellar classification, 01 natural sciences, Spectral line, Interplanetary scintillation, radio continuum: transients, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, media_common, radio continuum: galaxies, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Scintillation, Spectral density, Astronomy and Astrophysics, Quasar, Astrophysics - Astrophysics of Galaxies, radio continuum: ISM, 13. Climate action, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on a search for low-frequency radio variability in 944 bright (> 4Jy at 154 MHz) unresolved, extragalactic radio sources monitored monthly for several years with the Murchison Widefield Array. In the majority of sources we find very low levels of variability with typical modulation indices < 5%. We detect 15 candidate low frequency variables that show significant long term variability (>2.8 years) with time-averaged modulation indices M = 3.1 - 7.1%. With 7/15 of these variable sources having peaked spectral energy distributions, and only 5.7% of the overall sample having peaked spectra, we find an increase in the prevalence of variability in this spectral class. We conclude that the variability seen in this survey is most probably a consequence of refractive interstellar scintillation and that these objects must have the majority of their flux density contained within angular diameters less than 50 milli-arcsec (which we support with multi-wavelength data). At 154 MHz we demonstrate that interstellar scintillation time-scales become long (~decades) and have low modulation indices, whilst synchrotron driven variability can only produce dynamic changes on time-scales of hundreds of years, with flux density changes less than one milli-jansky (without relativistic boosting). From this work we infer that the low frequency extra-galactic southern sky, as seen by SKA-Low, will be non-variable on time-scales shorter than one year., 19 pages, 11 figures
Published: 2019

14. Multifrequency observations of SGR J1935+2154

Author: Marc Klein-Wolt, A. Addis, K. Gourdji, A. Possenti, Mateusz Malenta, M. Serylak, Elmar Körding, Mitchell B. Mickaliger, A. J. Cooper, Jason W. T. Hessels, Alessio Magro, Ramesh Karuppusamy, M. Geyer, D. J. Champion, C. G. Bassa, Giovanni Naldi, S. ter Veen, Kaustubh Rajwade, G. Desvignes, Vanessa McBride, Kerry Paterson, Laura Spitler, Germano Bianchi, Laura Driessen, Aditya Parthasarathy, Gianni Bernardi, Fabian Jankowski, Ralph A. M. J. Wijers, Patrick Woudt, Mayuresh Surnis, Benetge Perera, Marco Tavani, V. Venkatraman Krishnan, Marcus E. Lower, Antonia Rowlinson, Michael Kramer, V. I. Kondratiev, Vincent Morello, M. Caleb, Benjamin Stappers, Giancarlo Setti, Matthew Bailes, Mechiel Christiaan Bezuidenhout, Ian Heywood, Paul J. Groot, R. S. Le Poole, Weiwei Chen, M. Burgay, Giuseppe Pupillo, S. Buchner, Steven Bloemen, Ziggy Pleunis, Andrew Lyne, Kang Liu, Maura Pilia, P. M. Vreeswijk, D. L. A. Pieterse, ITA, GBR, AUS, High Energy Astrophys. & Astropart. Phys (API, FNWI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, LOFAR, Astrophysics, Magnetar, Astrophysics - high energy astrophysical phenomena, 01 natural sciences, Optical telescope, law.invention, Telescope, Radio telescope, 13. Climate action, Space and Planetary Science, law, 0103 physical sciences, Stars: magnetars, Optical emission spectroscopy, Fast radio bursts, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics
Abstract: Magnetars are a promising candidate for the origin of Fast Radio Bursts (FRBs). The detection of an extremely luminous radio burst from the Galactic magnetar SGR J1935+2154 on 2020 April 28 added credence to this hypothesis. We report on simultaneous and non-simultaneous observing campaigns using the Arecibo, Effelsberg, LOFAR, MeerKAT, MK2 and Northern Cross radio telescopes and the MeerLICHT optical telescope in the days and months after the April 28 event. We did not detect any significant single radio pulses down to fluence limits between 25 mJy ms and 18 Jy ms. Some observing epochs overlapped with times when X-ray bursts were detected. Radio images made on four days using the MeerKAT telescope revealed no point-like persistent or transient emission at the location of the magnetar. No transient or persistent optical emission was detected over seven days. Using the multi-colour MeerLICHT images combined with relations between DM, NH and reddening we constrain the distance to SGR J1935+2154, to be between 1.5 and 6.5 kpc. The upper limit is consistent with some other distance indicators and suggests that the April 28 burst is closer to two orders of magnitude less energetic than the least energetic FRBs. The lack of single-pulse radio detections shows that the single pulses detected over a range of fluences are either rare, or highly clustered, or both. It may also indicate that the magnetar lies somewhere between being radio-quiet and radio-loud in terms of its ability to produce radio emission efficiently., Comment: Accepted for publication in MNRAS. Corresponding author B. W. Stappers
Published: 2021

15. Murchison Widefield Array rapid-response observations of the short GRB 180805A

Author: B. W. Meyers, Martin Bell, Tara Murphy, Marcin Sokolowski, Paul Hancock, C. W. James, James Miller-Jones, J. Tian, Keith W. Bannister, D. L. Kaplan, Steven Tingay, Andrew Williams, Randall B. Wayth, Melanie Johnston-Hollitt, G. E. Anderson, Natasha Hurley-Walker, Antonia Rowlinson, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Astronomy & Astrophysics, Magnetar, 01 natural sciences, Redshift, Radio telescope, Interstellar medium, Neutron star, Space and Planetary Science, 0103 physical sciences, 0201 Astronomical and Space Sciences, 0299 Other Physical Sciences, Spectral resolution, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: Here we present stringent low-frequency 185MHz limits on coherent radio emission associated with a short gamma-ray burst (SGRB). Our observations of the short GRB 180805A were taken with the upgraded Murchison Widefield Array (MWA) rapid-response system, which triggered within 20s of receiving the transient alert from Swift, corresponding to 83.7s post-burst. The SGRB was observed for 30m, resulting in a 3sigma persistent flux density upper-limit of 40.2mJy/beam. Transient searches were conducted at the Swift position of this GRB on 0.5s, 5s, 30s, and 2m timescales, resulting in 3sigma limits of 570-1830, 270-630, 200-420, and 100-200mJy/beam, respectively. We also performed a dedispersion search for prompt signals at the position of the SGRB with a temporal and spectral resolution of 0.5s and 1.28MHz, resulting in a 6sigma fluence upper-limit range from 570Jyms at DM=3000pc/cm^3 (z~2.5) to 1750Jyms at DM=200pc/cm^3 (z~0.1). We compare the fluence prompt emission limit and the persistent upper-limit to SGRB coherent emission models assuming the merger resulted in a stable magnetar. Our observations were not sensitive enough to detect prompt emission associated with the alignment of magnetic fields of a binary neutron star just prior to the merger, from the interaction between the relativistic jet and the interstellar medium or persistent pulsar-like emission from the spin-down of the magnetar. However, in the case of a more powerful SGRB (a gamma-ray fluence an order of magnitude higher than GRB 180805A and/or a brighter X-ray counterpart), our MWA observations may be sensitive enough to detect coherent radio emission from the jet-ISM interaction and/or the magnetar remnant. Finally, we demonstrate that of all current low-frequency radio telescopes, only the MWA has the sensitivity and response times capable of probing prompt emission models associated with the initial SGRB merger event., Comment: 20 pages, 11 figures, accepted for publication in PASA
Published: 2021

16. Constraining a neutron star merger origin for localized fast radio bursts

Author: Antonia Rowlinson, Ralph A. M. J. Wijers, K. Gourdji, Adam Goldstein, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Light curve, Galaxy, Redshift, Supernova, Neutron star, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, education, Astrophysics::Galaxy Astrophysics, Fermi Gamma-ray Space Telescope
Abstract: What the progenitors of fast radio bursts (FRBs) are, and whether there are multiple types of progenitors are open questions. The advent of localized FRBs with host galaxy redshifts allows the various emission models to be directly tested for the first time. Given the recent localizations of two non-repeating FRBs (FRB 180924 and FRB 190523), we discuss a selection of FRB emission models and demonstrate how we can place constraints on key model parameters like the magnetic field strength and age of the putative FRB-emitting neutron star. In particular, we focus on models related to compact binary merger events involving at least one neutron star, motivated by commonalities between the host galaxies of the FRBs and the hosts of such merger events/short gamma-ray bursts (SGRBs). We rule out the possibility that either FRB was produced during the final inspiral stage of a merging binary system. Where possible, we predict the light curve of electromagnetic emission associated with a given model and use it to recommend multi-wavelength follow-up strategies that may help confirm or rule out models for future FRBs. In addition, we conduct a targeted sub-threshold search in Fermi Gamma-ray Burst Monitor data for potential SGRB candidates associated with either FRB, and show what a non-detection means for relevant models. The methodology presented in this study may be easily applied to future localized FRBs, and adapted to sources with possibly core-collapse supernova progenitors, to help constrain potential models for the FRB population at large., Comment: MNRAS accepted version. Published in MNRAS, 12 pages, 6 figures
Published: 2020

17. Long-term study of extreme giant pulses from PSR B0950+08 with AARTFAAC

Author: Antonia Rowlinson, Peeyush Prasad, Mark Kuiack, Aleksandar Shulevski, Folkert Huizinga, Ralph A. M. J. Wijers, Gijs Molenaar, High Energy Astrophys. & Astropart. Phys (API, FNWI), and API Other Research (FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Northern Hemisphere, FOS: Physical sciences, Astronomy and Astrophysics, Ranging, LOFAR, Astrophysics, Low frequency, 01 natural sciences, Fluence, Spectral line, Pulsar, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Order of magnitude
Abstract: We report on the detection of extreme giant pulses (GPs) from one of the oldest-known pulsars, the highly variable PSR B0950+08, with the Amsterdam-ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC), a parallel transient detection instrument operating as a subsystem of the LOw Frequency ARray (LOFAR). During processing of our Northern Hemisphere survey for low-frequency radio transients, a sample of 275 pulses with fluences ranging from 42 to 177 kJy ms were detected in one-second snapshot images. The brightest pulses are an order of magnitude brighter than those previously reported at 42 and 74 MHz, on par with the levels observed in a previous long-term study at 103 MHz. Both their rate and fluence distribution differ between and within the various studies done to date. The GP rate is highly variable, from 0 to 30 per hour, with only two three-hour observations accounting for nearly half of the pulses detected in the 96 h surveyed. It does not vary significantly within a few-hour observation, but can vary strongly one from day to the next. The spectra appear strongly and variably structured, with emission sometimes confined to a single 195.3 kHz subband, and the pulse spectra changing on a timescale of order 10 min., 10 pages, 9 figures, 1 table. Submitted to MNRAS
Published: 2020

18. A MeerKAT survey of nearby nova-like cataclysmic variables

Author: M. L. Pretorius, N. Castro Segura, Kunal Mooley, David R. Williams, Ian Heywood, Antonia Rowlinson, Benjamin Stappers, R. P. Armstrong, Ralph A. M. J. Wijers, Paul J. Groot, D. M. Hewitt, Vanessa McBride, A. J. van der Horst, Christian Knigge, Rob Fender, Elmar Koerding, Assaf Horesh, E. Tremou, James Miller-Jones, Patrick Woudt, High Energy Astrophys. & Astropart. Phys (API, FNWI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Power law, Luminosity, stars: jets, X-rays: binaries, accretion, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, white dwarfs, Physics, novae, High Energy Astrophysical Phenomena (astro-ph.HE), cataclysmic variables, Accretion (meteorology), 010308 nuclear & particles physics, Spectral density, White dwarf, Astronomy and Astrophysics, Nova (laser), accretion discs, Neutron star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, System parameters, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], radio continuum: stars
Abstract: We present the results of MeerKAT radio observations of eleven nearby novalike cataclysmic variables. We have detected radio emission from IM Eri, RW Sex, V3885 Sgr and V603 Aql. While RW Sex, V3885 Sgr and V603 Aql had been previously detected, this is the first reported radio detection of IM Eri. Our observations have doubled the sample of non-magnetic CVs with sensitive radio data. We observe that at our radio detection limits, a specific optical luminosity $\gtrsim 2.2\times 10^{18}$ erg/s/Hz (corresponding to $M_V \lesssim 6.0$) is required to produce a radio detection. We also observe that the X-ray and radio luminosities of our detected novalikes are on an extension of the $L_{X} \propto L_{R}^{\sim 0.7}$ power law originally proposed for non-pulsating neutron star low-mass X-ray binaries. We find no other correlations between the radio emission and emission in other wavebands or any other system parameters for the existing sample of radio-detected non-magnetic CVs. We measure in-band (0.9-1.7 GHz) radio spectral indices that are consistent with reports from earlier work. Finally, we constructed broad spectral energy distributions for our sample from published multi-wavelength data, and use them to place constraints on the mass transfer rates of these systems., Comment: 16 pages, 9 figures, accepted to MNRAS
Published: 2020

19. A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances

Author: M. Iacobelli, M. A. Garrett, I. Max Avruch, Bartosz Dabrowski, Hanna Rothkaehl, Richard Fallows, Michiel van Haarlem, Olaf Wucknitz, A. W. Gunst, Tom Allbrook, Jean Matthias Grießmeier, Harvey Butcher, Christian Vocks, Jörg R. Hörandel, Vishambhar Pandey, Léon V. E. Koopmans, Anna Nelles, Biagio Forte, Barbara Matyjasiak, P. Maat, Gareth Dorrian, Thomas M. O. Franzen, M. Ruiter, Ashish Asgekar, Oleg Smirnov, Ilse van Bemmel, Antonia Rowlinson, Matthijs H. D. van der Wiel, M. Serylak, Ivan Astin, Dominik J. Schwarz, Mark J. Bentum, Arnold van Ardenne, Matthias Hoeft, Gottfried Mann, S. Duscha, Alex Arnold, Huib Intema, H. Paas, S. Damstra, Francesco de Gasperin, James M. Anderson, Jochen Eislöffel, Maaijke Mevius, Benedetta Ciardi, Andrzej Krankowski, M. Carmen Toribio, Alan Wood, Satyendra Thoudam, Aleksander Shulevski, Mario M. Bisi, Ralph A. M. J. Wijers, Pietro Zucca, Philippe Zarka, Wolfgang Reich, Marian Soida, Rene C. Vermeulen, Matthias Steinmetz, Netherlands Institute for Radio Astronomy (ASTRON), Environmental Systems Science Centre [Reading] (ESSC), University of Reading (UOR), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Department of Computer Science [Chapel Hill], University of North Carolina [Chapel Hill] (UNC), University of North Carolina System (UNC)-University of North Carolina System (UNC), Eindhoven Technical University, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Thüringer Landessternwarte Tautenburg (TLS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), SKA South Africa, Ska South Africa, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Astronomy
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Astronomy, FOS: Physical sciences, Instability mechanisms, lcsh:QC851-999, 01 natural sciences, Physics::Geophysics, Physics - Geophysics, travelling ionospheric disturbances, Interplanetary scintillation, Physics - Space Physics, Ionospheric scintillation, 0103 physical sciences, ddc:550, Gravity wave, Travelling ionospheric disturbances, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], Earth and Planetary Astrophysics (astro-ph.EP), Scintillation, Scattering, LOFAR, Geodesy, Space Physics (physics.space-ph), Geophysics (physics.geo-ph), instability mechanisms, Earth's magnetic field, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, lcsh:Meteorology. Climatology, Ionosphere, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Ionosonde, Astrophysics - Earth and Planetary Astrophysics
Abstract: This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cas A, taken overnight on 18-19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10-80MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR "core" reveals two different velocities in the scintillation pattern: a primary velocity of ~30m/s with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110m/s with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller--scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported., Comment: 24 pages, 16 figures. Accepted for open-access publication in the Journal of Space Weather and Space Climate. For associated movie file, see https://www.swsc-journal.org/10.1051/swsc/2020010/olm
Published: 2020

20. An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070

Author: Robert Beswick, Elmar Körding, Assaf Horesh, Rob Fender, David Titterington, Sara Motta, Patrick A. Woudt, David A. H. Buckley, Stephane Corbel, David A. Green, Joe Bright, Elena Gallo, J. Moldon, Antonia Rowlinson, Ian Heywood, R. P. Armstrong, Ralph A. M. J. Wijers, Evangelia Tremou, A. J. van der Horst, Gregory R. Sivakoff, Vanessa McBride, James Miller-Jones, David R. Williams, Thomas D. Russell, Richard M. Plotkin, Alexandra J. Tetarenko, Paul J. Groot, Jeroen Homan, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Bright, JS [0000-0002-7735-5796], Miller-Jones, JCA [0000-0003-3124-2814], Sivakoff, GR [0000-0001-6682-916X], Corbel, S [0000-0001-5538-5831], Tetarenko, AJ [0000-0003-3906-4354], Russell, TD [0000-0002-7930-2276], Green, DA [0000-0003-3189-9998], Groot, PJ [0000-0002-4488-726X], Apollo - University of Cambridge Repository, Science and Technology Facilities Council (UK), Sorbonne Université, Oxford Hintze Centre for Astrophysical Surveys (UK), Ministerio de Ciencia, Innovación y Universidades (España), European Commission, European Research Council, Australian Research Council, German-Israeli Foundation for Scientific Research and Development, High Energy Astrophys. & Astropart. Phys (API, FNWI), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 7. Clean energy, 01 natural sciences, Collimated light, law.invention, General Relativity and Quantum Cosmology, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, Ejecta, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, astro-ph.HE, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Jet (fluid), Superluminal motion, Astronomy and Astrophysics, Particle acceleration, Wavelength, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Flare
Abstract: Black holes in binary systems execute patterns of outburst activity where two characteristic X-ray states are associated with different behaviours observed at radio wavelengths. The hard state is associated with radio emission indicative of a continuously replenished, collimated, relativistic jet, whereas the soft state is rarely associated with radio emission, and never continuously, implying the absence of a quasi-steady jet. Here we report radio observations of the black hole transient MAXI J1820+070 during its 2018 outburst. As the black hole transitioned from the hard to soft state, we observed an isolated radio flare, which, using high-angular-resolution radio observations, we connect with the launch of bipolar relativistic ejecta. This flare occurs as the radio emission of the core jet is suppressed by a factor of over 800. We monitor the evolution of the ejecta over 200 days and to a maximum separation of 10″, during which period it remains detectable due to in situ particle acceleration. Using simultaneous radio observations sensitive to different angular scales, we calculate an accurate estimate of energy content of the approaching ejection. This energy estimate is far larger than that derived from the state transition radio flare, suggesting a systematic underestimate of jet energetics. © 2020, The Author(s), under exclusive licence to Springer Nature Limited., J.S.B. acknowledges the support of a Science and Technologies Facilities Council Studentship. E.T. acknowledges financial support from the UnivEarthS Labex programme of Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). D.A.H.B. acknowledges support by the National Research Foundation. P.A.W. acknowledges support from the NRF and UCT. J.C.A.M.-J. is the recipient of an Australian Research Council Future Fellowship (FT140101082), funded by the Australian government. A.H. acknowledges that this research was supported by a grant from the GIF, the German-Israeli Foundation for Scientific Research and Development. I.H. and D.R.A.W. acknowledge support from the Oxford Hintze Centre for Astrophysical Surveys, which is funded through generous support from the Hintze Family Charitable Foundation. J.M. acknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and from the grant RTI2018-096228-B-C31 (MICIU/FEDER, EU). The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Technology. We thank the staff of the Mullard Radio Astronomy Observatory for their invaluable assistance in the commissioning, maintenance and operation of AMI, which is supported by the universities of Cambridge and Oxford. We acknowledge support from the European Research Council under grant ERC-2012-StG-307215 LODESTONE. We thank the Swift team for performing observations promptly on short notice. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC. We acknowledge the use of the Inter-University Institute for Data Intensive Astronomy (IDIA) data-intensive research cloud for data processing. IDIA is a South African university partnership involving the University of Cape Town, the University of Pretoria and the University of the Western Cape. We thank the International Space Science Institute in Bern, Switzerland for support and hospitality for the team meeting 'Looking at the disc-jet coupling from different angles: inclination dependence of black-hole accretion observables'.
Published: 2020

21. MKT J170456.2–482100: the first transient discovered by MeerKAT

Author: A. J. van der Horst, Iain McDonald, Vanessa McBride, Patrick A. Woudt, Kaustubh Rajwade, Rob Fender, Enrico J. Kotze, Manisha Caleb, Benjamin Stappers, Elmar Koerding, Assaf Horesh, Antonia Rowlinson, Ian Heywood, D. A. H. Buckley, Ralph A. M. J. Wijers, Paul J. Groot, Kunal Mooley, Evangelia Tremou, Richard Armstrong, Laura Driessen, James Miller-Jones, S. B. Potter, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), High Energy Astrophys. & Astropart. Phys (API, FNWI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112))
Subjects: peculiar [stars], Binary number, FOS: Physical sciences, Astrophysics, 01 natural sciences, Photometry (optics), spectroscopic [Binaries], Coincident, 0103 physical sciences, stars: activity, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), activity [stars], 010308 nuclear & particles physics, stars: peculiar, Astronomy and Astrophysics, Light curve, Radial velocity, Amplitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, flare [stars], stars: flare, Maximum flux, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], binaries: spectroscopic
Abstract: We report the discovery of the first transient with MeerKAT, MKT J170456.2$-$482100, discovered in ThunderKAT images of the low mass X-ray binary GX339$-$4. MKT J170456.2$-$482100 is variable in the radio, reaching a maximum flux density of $0.71\pm0.11\,\mathrm{mJy}$ on 2019 Oct 12, and is undetected in 15 out of 48 ThunderKAT epochs. MKT J170456.2$-$482100 is coincident with the chromospherically active K-type sub-giant TYC 8332-2529-1, and $\sim18\,\mathrm{years}$ of archival optical photometry of the star shows that it varies with a period of $21.25\pm0.04\,\mathrm{days}$. The shape and phase of the optical light curve changes over time, and we detect both X-ray and UV emission at the position of MKT J170456.2$-$482100, which may indicate that TYC 8332-2529-1 has large star spots. Spectroscopic analysis shows that TYC 8332-2529-1 is in a binary, and has a line-of-sight radial velocity amplitude of $43\,\mathrm{km\,s^{-1}}$. We also observe a spectral feature in anti-phase with the K-type sub-giant, with a line-of-sight radial velocity amplitude of $\sim12\pm10\,\mathrm{km\,s^{-1}}$, whose origins cannot currently be explained. Further observations and investigation are required to determine the nature of the MKT J170456.2$-$482100 system., Comment: 16 pages, 12 figures, 7 tables
Published: 2020

22. LOFAR 144-MHz follow-up observations of GW170817

Author: Oleg Smirnov, Martin J. Hardcastle, P. Zarka, Adam Stewart, H. Paas, D. Carbone, P. Maat, Dominik J. Schwarz, M. C. Toribio, David A. Nichols, G. Mann, Rudy Wijnands, A. J. van der Horst, Evan Keane, H. J. A. Röttgering, Olaf Wucknitz, C. Tasse, T. Muñoz-Darias, Henk Mulder, M. H. D. van der Wiel, Kenta Hotokezaka, M. P. van Haarlem, Stephane Corbel, J. B. R. Oonk, S. ter Veen, A. W. Gunst, W. N. Brouw, Casey J. Law, M. Iacobelli, K. Gourdji, Samaya Nissanke, J. W. Broderick, Timothy W. Shimwell, R. Pekal, Rob Fender, W. Reich, James M. Anderson, Matthias Hoeft, Anna Nelles, R. Blaauw, Luitje Koopmans, J. van Leeuwen, Aleksandar Shulevski, R. J. van Weeren, Pietro Zucca, Marian Soida, Martin Bell, Ralph A. M. J. Wijers, Vanessa A. Moss, M. Pandey-Pommier, Thomas M. O. Franzen, Antonia Rowlinson, Anjali A. A. Piette, S. Duscha, Richard Fallows, M. A. Garrett, Peter G. Jonker, Mark J. Bentum, J.-M. Grießmeier, M. de Vos, B. Ciardi, Jörg R. Hörandel, E. Jütte, C. Vocks, M. Serylak, Andrzej Krankowski, Marcus Brüggen, Jochen Eislöffel, M. Pietka, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Astroparticle Physics (IHEF, IoP, FNWI), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Astronomy, and Kapteyn Astronomical Institute
Subjects: Astronomy, FOS: Physical sciences, Binary number, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Radio spectrum, stars: neutron, neutron [stars], 0201 Astronomical and Space Sciences, 0103 physical sciences, 14. Life underwater, Center frequency, 010306 general physics, stars [radio continuum], 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, [PHYS]Physics [physics], Spectral index, Gravitational wave, Astronomy and Astrophysics, LOFAR, Afterglow, Neutron star, gravitational waves, Space and Planetary Science, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], radio continuum: stars
Abstract: We present low-radio-frequency follow-up observations of AT 2017gfo, the electromagnetic counterpart of GW170817, which was the first binary neutron star merger to be detected by Advanced LIGO-Virgo. These data, with a central frequency of 144 MHz, were obtained with LOFAR, the Low-Frequency Array. The maximum elevation of the target is just 13.7 degrees when observed with LOFAR, making our observations particularly challenging to calibrate and significantly limiting the achievable sensitivity. On time-scales of 130-138 and 371-374 days after the merger event, we obtain 3$\sigma$ upper limits for the afterglow component of 6.6 and 19.5 mJy beam$^{-1}$, respectively. Using our best upper limit and previously published, contemporaneous higher-frequency radio data, we place a limit on any potential steepening of the radio spectrum between 610 and 144 MHz: the two-point spectral index $\alpha^{610}_{144} \gtrsim -2.5$. We also show that LOFAR can detect the afterglows of future binary neutron star merger events occurring at more favourable elevations., Comment: 9 pages, 2 figures, accepted for publication in MNRAS
Published: 2020

23. AARTFAAC flux density calibration and Northern hemisphere catalogue at 60 MHz

Author: Peeyush Prasad, Ralph A. M. J. Wijers, Gijs Molenaar, Folkert Huizinga, Mark Kuiack, Antonia Rowlinson, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Gravitation and Astroparticle Physics Amsterdam
Subjects: Physics, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Northern Hemisphere, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, Magnetar, 01 natural sciences, Astron, Apparent magnitude, Space and Planetary Science, 0103 physical sciences, Calibration, Astrophysics - Instrumentation and Methods for Astrophysics, Blazar, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics
Abstract: We present a method for calibrating the flux density scale for images generated by the Amsterdam ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC). AARTFAAC produces a stream of all-sky images at a rate of one second in order to survey the Northern Hemisphere for short duration, low frequency transients, such as the prompt EM counterpart to gravitational wave events, magnetar flares, blazars, and other as of yet unobserved phenomena. Therefore, an independent flux density scaling solution per image is calculated via bootstrapping, comparing the measured apparent brightness of sources in the field to a reference catalogue. However, the lack of accurate flux density measurements of bright sources below 74 MHz necessitated the creation of the AARTFAAC source catalogue, at 60 MHz, which contains 167 sources across the Northern Hemisphere. Using this as a reference results in a sufficiently high number of detected sources in each image to calculate a stable and accurate flux scale per one second snapshot, in real-time., Accepted by MNRAS, 25 pages, 14 figures
Published: 2018

24. Investigating the nature of the INTEGRAL gamma-ray bursts and sub-threshold triggers with Swift follow-up

Author: Antonia Rowlinson, J. P. Osborne, Sandro Mereghetti, D. Gotz, K. Wiersema, A. J. Bird, Thomas J. Maccarone, N. Gehrels, Nial R. Tanvir, P. T. O'Brien, R. L. C. Starling, A. B. Higgins, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Laboratoire AIM, Université Paris Diderot - Paris 7 ( UPD7 ) -Centre d'Etudes de Saclay, and Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112))
Subjects: Swift, Active galactic nucleus, 010504 meteorology & atmospheric sciences, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astrophysics, 01 natural sciences, Coincident, 0103 physical sciences, education, 010303 astronomy & astrophysics, Alert system, 0105 earth and related environmental sciences, computer.programming_language, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, Low fluence, Astronomy and Astrophysics, Space and Planetary Science, Sub threshold, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, computer
Abstract: We explore the potential of INTEGRAL to improve our understanding of the low fluence regime for explosive transients, such as GRBs. We probe the nature of the so-called "WEAK" INTEGRAL triggers, when the gamma-ray instruments record intensity spikes that are below the usual STRONG significance thresholds. In a targeted Swift follow-up campaign, we observed 15 WEAK triggers. We find six of these can be classified as GRBs. This includes GRB150305A, a GRB discovered from our campaign alone. We also identified a source coincident with one trigger, IGRW151019, as a candidate AGN. We show that real events such as GRBs exist within the IBAS WEAK trigger population. A comparison of the fluence distributions of the full INTEGRAL IBAS and Swift BAT GRB samples showed that the two are similar. We also find correlations between the prompt gamma-ray and X-ray properties of the two samples, supporting previous investigations. We find that both satellites reach similar, low fluence levels regularly, although Swift is more sensitive to short, low fluence GRBs., 12 pages, 8 figures, accepted by MNRAS. Minor typos changed and a reference added
Published: 2017

25. Evidence for a TDE origin of the radio transient Cygnus A-2

Author: Aneta Siemiginowska, Paul Nulsen, Antonia Rowlinson, M. N. de Vries, Michael W. Wise, Christopher S. Reynolds, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Brightness, Active galactic nucleus, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Light curve, 01 natural sciences, Afterglow, Black hole, Tidal disruption event, Space and Planetary Science, 0103 physical sciences, Fundamental plane (elliptical galaxies), Cygnus A, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: In 2015, a radio transient named Cygnus A-2 was discovered in Cygnus A with the Very Large Array. Because of its radio brightness ($\nu F_{\nu} \approx 6 \times 10^{39}$ erg s$^{-1}$), this transient likely represents a secondary black hole in orbit around the AGN. Using {\it Chandra} ACIS observations from 2015 to 2017, we have looked for an X-ray counterpart to Cygnus A-2. The separation of 0.42 arcsec means that Cygnus A-2 can not be spatially resolved, but by comparing the data with simulated \texttt{marx} data, we put an upper limit to the 2-10 keV X-ray luminosity of Cygnus A-2 of $1 \times 10^{43}$ erg s$^{-1}$. Using the Fundamental Plane for accreting black holes, we find that our upper limit to the X-ray flux of Cygnus A-2 in 2015-2017 disfavours the interpretation of Cygnus A-2 as a steadily accreting black hole. We suggest instead that Cygnus A-2 is the radio afterglow of a tidal disruption event (TDE), and that a peak in the 2-10 keV luminosity of the nuclear region in 2013, when it was observed by {\it Swift} and {\it NuSTAR}, is X-ray emission from the TDE. A TDE could naturally explain the X-ray light curve of the nuclear region, as well as the appearance of a short-lived, fast, and ionized outflow previously detected in the 2013 {\it NuSTAR} spectrum. Both the radio and X-ray luminosities fall in between typical luminosities for 'thermal' and 'jetted' TDE types, suggesting that Cygnus A-2 would be unlike previously seen TDE's., Comment: 14 pages, 7 figures, accepted for publication in MNRAS
Published: 2019

26. Identifying transient and variable sources in radio images

Author: P. Zarka, B. Scheers, Y.N. Cendes, Tim D. Staley, John D. Swinbank, Adam Stewart, J.-M. Grießmeier, J. van Leeuwen, Michael Bell, Antonia Rowlinson, Sean Farrell, D. Carbone, Rob Fender, C. J. Law, Gijs Molenaar, Jochen Eislöffel, Ralph A. M. J. Wijers, A. J. van der Horst, J. W. Broderick, Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Sydney Institute for Astronomy (SIfA), The University of Sydney, University of Washington [Seattle], Department of Physics and Astronomy, Texas Tech University [Lubbock] (TTU), Dunlap Institute for Astronomy and Astrophysics [Toronto], University of Toronto, Oxford Astrophysics, University of Oxford [Oxford], Department of Physics the George Washington University, Department of Physics and Electronics, Rhodes University, Grahamstown, Centrum Wiskunde & Informatica (CWI), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Technology Sydney (UTS), Thüringer Landessternwarte Tautenburg (TLS), Department of Astronomy [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Project: 247295,EC:FP7:ERC,ERC-2009-AdG,AARTFAAC(2010), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), European Project: 617199,EC:FP7:ERC,ERC-2013-CoG,ALERT(2014), Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands, University of Oxford, University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Computer science, Data analysis, FOS: Physical sciences, Methods Data analysis Methods Statistical Radio continuum General, ComputerApplications_COMPUTERSINOTHERSYSTEMS, computer.software_genre, 01 natural sciences, 0103 physical sciences, Methods, General, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), computer.programming_language, [PHYS]Physics [physics], 010308 nuclear & particles physics, Anomaly detection algorithm, Astronomy and Astrophysics, LOFAR, Python (programming language), Statistical, Computer Science Applications, Pipeline transport, Radio continuum, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Snapshot (computer storage), Data mining, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], computer
Abstract: With the arrival of a number of wide-field snapshot image-plane radio transient surveys, there will be a huge influx of images in the coming years making it impossible to manually analyse the datasets. Automated pipelines to process the information stored in the images are being developed, such as the LOFAR Transients Pipeline, outputting light curves and various transient parameters. These pipelines have a number of tuneable parameters that require training to meet the survey requirements. This paper utilises both observed and simulated datasets to demonstrate different machine learning strategies that can be used to train these parameters. The datasets used are from LOFAR observations and we process the data using the LOFAR Transients Pipeline; however the strategies developed are applicable to any light curve datasets at different frequencies and can be adapted to different automated pipelines. These machine learning strategies are publicly available as Python tools that can be downloaded and adapted to different datasets (https://github.com/AntoniaR/TraP_ML_tools)., Comment: Astronomy & Computing Accepted, 25 pages, 20 figures
Published: 2019

27. The LOFAR Two-metre Sky Survey. II. First data release

Author: Eskil Varenius, Huub Röttgering, Magdalena Kunert-Bajraszewska, Ricardo Genova-Santos, Judith H. Croston, D. Nisbet, R. Lakhoo, R. Kondapally, F. Savini, Joseph R. Callingham, A. O. Clarke, H. R. Stacey, M. H. D. van der Wiel, Isabella Prandoni, Antonia Rowlinson, R. Pizzo, Gianfranco Brunetti, David Bacon, George K. Miley, Marcus Brüggen, L. Alegre, R.-J. Dettmar, C. Dumba, R. J. van Weeren, Volker Heesen, Stephen Bourke, G. Calistro Rivera, A. Botteon, J. Sabater, M. Mirmont, G. Gürkan, Andrea Merloni, Torsten A. Enßlin, Marek Jamrozy, Philip Best, A. Drabent, Marcellin Atemkeng, Glenn J. White, R. C. Vermeulen, Wolfgang Reich, Neal Jackson, Chiara Ferrari, Marco Iacobelli, Huib Intema, J. B. R. Oonk, D. N. Hoang, John Conway, A. Wilber, Marisa Brienza, T. J. Dijkema, B. Webster, M. A. Garrett, Simon Perkins, A. P. Mechev, Shane O'Sullivan, Christopher J. Conselice, I. van Bemmel, Annalisa Bonafede, Oleg Smirnov, John L. Quinn, John McKean, G. Kokotanekov, Subhash C. Mandal, Daniel J. Smith, C. L. Hale, Arti Goyal, Błażej Nikiel-Wroczyński, K. L. Emig, S. Urquhart, Marijke Haverkorn, Timothy W. Shimwell, R. Morganti, Michael W. Wise, Elizabeth K. Mahony, Beatriz Mingo, Arpad Miskolczi, C. A. Jackson, Leah K. Morabito, D. A. Rafferty, A. Saxena, C. Roskowinski, Rachel Cochrane, C. Schrijvers, M. Mevius, Wendy L. Williams, E. Bonnassieux, Rossella Cassano, Matthias Hoeft, Krzysztof T. Chyzy, Dominik J. Schwarz, B. Hugo, Robert Beswick, George Heald, C. Tasse, S. Mooney, Jeremy J. Harwood, Emanuela Orru, Martin J. Hardcastle, Kenneth Duncan, S. S. Sridhar, Cathy Horellou, Matt J. Jarvis, L. Bester, F. de Gasperin, Aleksandar Shulevski, A. Danezi, V. H. Mahatma, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Shimwell T.W., Tasse C., Hardcastle M.J., Mechev A.P., Williams W.L., Best P.N., Rottgering H.J.A., Callingham J.R., Dijkema T.J., De Gasperin F., Hoang D.N., Hugo B., Mirmont M., Oonk J.B.R., Prandoni I., Rafferty D., Sabater J., Smirnov O., Van Weeren R.J., White G.J., Atemkeng M., Bester L., Bonnassieux E., Bruggen M., Brunetti G., Chy K.T., Cochrane R., Conway J.E., Croston J.H., Danezi A., Duncan K., Haverkorn M., Heald G.H., Iacobelli M., Intema H.T., Jackson N., Jamrozy M., Jarvis M.J., Lakhoo R., Mevius M., Miley G.K., Morabito L., Morganti R., Nisbet D., Orru E., Perkins S., Pizzo R.F., Schrijvers C., Smith D.J.B., Vermeulen R., Wise M.W., Alegre L., Bacon D.J., Van Bemmel I.M., Beswick R.J., Bonafede A., Botteon A., Bourke S., Brienza M., Calistro Rivera G., Cassano R., Clarke A.O., Conselice C.J., Dettmar R.J., Drabent A., Dumba C., Emig K.L., Ensslin T.A., Ferrari C., Garrett M.A., Genova-Santos R.T., Goyal A., Gurkan G., Hale C., Harwood J.J., Heesen V., Hoeft M., Horellou C., Jackson C., Kokotanekov G., Kondapally R., Kunert-Bajraszewska M., Mahatma V., Mahony E.K., Mandal S., McKean J.P., Merloni A., Mingo B., Miskolczi A., Mooney S., Nikiel-Wroczynski B., O'Sullivan S.P., Quinn J., Reich W., Roskowinski C., Rowlinson A., Savini F., Saxena A., Schwarz D.J., Shulevski A., Sridhar S.S., Stacey H.R., Urquhart S., Van Der Wiel M.H.D., Varenius E., Webster B., and Wilber A.
Subjects: Astronomy, radio continuum: general, Flux, techniques: image processing, Astrophysics, 01 natural sciences, CLUSTER ENVIRONMENTS, ST/M001229/1, Survey, 010303 astronomy & astrophysics, SOUTHERN SKY, media_common, astro-ph.HE, Physics, CALIBRATION, High Energy Astrophysical Phenomena (astro-ph.HE), image processing [techniques], UNDERSTANDING RADIO POLARIMETRY, ST/R00109X/1, ST/P000096/1, astro-ph.CO, general [radio continuum], Catalog, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), astro-ph.GA, media_common.quotation_subject, FOS: Physical sciences, Declination, surveys, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], AGN, Instrumentation and Methods for Astrophysics (astro-ph.IM), STFC, ST/M001326/1, 010308 nuclear & particles physics, RCUK, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, GALAXY, ST/M001008/1, Space and Planetary Science, Sky, IMAGING SURVEY, DISCOVERY, Astrophysics of Galaxies (astro-ph.GA), FLUX-DENSITY SCALE, Right ascension, EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], catalogs, astro-ph.IM
Abstract: The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations are now 20% complete. We present our first full-quality public data release. For this data release 424 square degrees, or 2% of the eventual coverage, in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45$^\circ$00$'$00$''$ to 57$^\circ$00$'$00$''$) were mapped using a fully automated direction-dependent calibration and imaging pipeline that we developed. A total of 325,694 sources are detected with a signal of at least five times the noise, and the source density is a factor of $\sim 10$ higher than the most sensitive existing very wide-area radio-continuum surveys. The median sensitivity is S$_{\rm 144 MHz} = 71\,\mu$Jy beam$^{-1}$ and the point-source completeness is 90% at an integrated flux density of 0.45mJy. The resolution of the images is 6$''$ and the positional accuracy is within 0.2$''$. This data release consists of a catalogue containing location, flux, and shape estimates together with 58 mosaic images that cover the catalogued area. In this paper we provide an overview of the data release with a focus on the processing of the LOFAR data and the characteristics of the resulting images. In two accompanying papers we provide the radio source associations and deblending and, where possible, the optical identifications of the radio sources together with the photometric redshifts and properties of the host galaxies. These data release papers are published together with a further $\sim$20 articles that highlight the scientific potential of LoTSS., Comment: 16 figures, 1 table and 22 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal
Published: 2019

28. Needle-like structures discovered on positively charged lightning branches

Author: S. ter Veen, A. W. Gunst, M. A. Garrett, Laura Rossetto, A. J. van der Horst, J.-M. Grießmeier, R. Blaauw, Mark J. Bentum, R. J. van Weeren, Jörg P. Rachen, B. Ciardi, Pietro Zucca, Heino Falcke, R. Pekal, Aleksandar Shulevski, Anna Nelles, P. Maat, M. J. Norden, H. Paas, James M. Anderson, Stijn Buitink, Katie Mulrey, Richard Fallows, M. C. Toribio, J. Sluman, Luitje Koopmans, Olaf Scholten, Oleg Smirnov, Jörg R. Hörandel, Jochen Eislöffel, Roberto Pizzo, Hanna Rothkaehl, H. J. A. Röttgering, Harvey Butcher, P. Zarka, Olaf Wucknitz, Antonia Rowlinson, T. N. G. Trinh, Andrzej Krankowski, S. Duscha, Arthur Corstanje, Tim Huege, I. M. Avruch, Vishambhar Pandey, Ralph A. M. J. Wijers, M. Iacobelli, Pragati Mitra, Jason W. T. Hessels, Matthias Hoeft, A. van Ardenne, Tobias Winchen, Antonio Bonardi, Dominik J. Schwarz, W. N. Brouw, Brian Hare, Michel Tagger, W. Reich, J. W. Broderick, E. de Geus, Pim Schellart, Marcus Brüggen, M. P. van Haarlem, M. Pandey-Pommier, Joseph R. Dwyer, Marian Soida, High Energy Astrophys. & Astropart. Phys (API, FNWI), KVI Center for Advanced Radiation Technology, University of Groningen [Groningen], Radboud university [Nijmegen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Netherlands Institute for Radio Astronomy (ASTRON), Astrophysical Institute, Vrije Universiteit Brussel, Vrije Universiteit [Brussels] (VUB), Karlsruher Institut für Technologie (KIT), Milieux aquatiques, écologie et pollutions (UR MALY), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), SRON Netherlands Institute for Space Research (SRON), University of Southampton, Kapteyn Astronomical Institute [Groningen], Jacobs University [Bremen], Research School of Astronomy and Astrophysics [Canberra] (RSAA), Australian National University (ANU), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Medstar Research Institute, Thüringer Landessternwarte Tautenburg (TLS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Institute of Geodesy, Center for Information Technology CIT, Université de Groningen, Centre de Recherche Astrophysique de Lyon (CRAL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Department of Applied Chemistry (DAC), Banaras Hindu University [Varanasi] (BHU), Max-Planck-Institut für Radioastronomie (MPIFR), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk (PAN), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Project: 227610,EC:FP7:ERC,ERC-2008-AdG,LOFAR-AUGER(2009), European Project: 640130,H2020,ERC-2014-STG,LOFAR(2015), Center for Wireless Technology Eindhoven, Electromagnetics, EM for Radio Science Lab, Physics, Elementary Particle Physics, Astronomy and Astrophysics Research Group, Department of Bio-engineering Sciences, Faculty of Sciences and Bioengineering Sciences, Radboud University [Nijmegen], Vrije Universiteit Brussel (VUB), Global Aerospace, Adran Ffiseg, Prifysgol Cymru Aberystwyth, Universiteit Leiden, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Department of Physics the George Washington University, Space Radio-Diagnostic Research Center [Olsztyn], University of Warmia and Mazury [Olsztyn], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Interactions Son Musique Mouvement, Sciences et Technologies de la Musique et du Son (STMS), Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Rhodes University, Grahamstown, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-IRCAM-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-IRCAM-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astronomy, and Research unit Astroparticle Physics
Subjects: [PHYS]Physics [physics], Physics, Multidisciplinary, 010504 meteorology & atmospheric sciences, Astronomy, 010502 geochemistry & geophysics, 01 natural sciences, Lightning, [SDU]Sciences of the Universe [physics], Natural phenomenon, ddc:530, Spatiotemporal resolution, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Initiation point, 0105 earth and related environmental sciences
Abstract: Nature / Physical science 568(7752), 360 - 363 (2019). doi:10.1038/s41586-019-1086-6, Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends—called positive and negative leaders. Negative leaders propagate in discrete steps, emitting copious radio pulses in the 30–300-megahertz frequency band that can be remotely sensed and imaged with high spatial and temporal resolution. Positive leaders propagate more continuously and thus emit very little high-frequency radiation. Radio emission from positive leaders has nevertheless been mapped, and exhibits a pattern that is different from that of negative leaders. Furthermore, it has been inferred that positive leaders can become transiently disconnected from negative leaders, which may lead to current pulses that both reconnect positive leaders to negative leaders and cause multiple cloud-to-ground lightning events. The disconnection process is thought to be due to negative differential resistance, but this does not explain why the disconnections form primarily on positive leaders, or why the current in cloud-to-ground lightning never goes to zero. Indeed, it is still not understood how positive leaders emit radio-frequency radiation or why they behave differently from negative leaders. Here we report three-dimensional radio interferometric observations of lightning over the Netherlands with unprecedented spatiotemporal resolution. We find small plasma structures—which we call ‘needles’—that are the dominant source of radio emission from the positive leaders. These structures appear to drain charge from the leader, and are probably the reason why positive leaders disconnect from negative ones, and why cloud-to-ground lightning connects to the ground multiple times., Published by Macmillan28177, London
Published: 2019

29. Constraining coherent low frequency radio flares from compact binary mergers

Author: G. E. Anderson, Antonia Rowlinson, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, Magnetar, 01 natural sciences, Radio telescope, Neutron star, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, education, Gamma-ray burst, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The presence and detectability of coherent radio emission from compact binary mergers (containing at least one neutron star) remains poorly constrained due to large uncertainties in the models. These compact binary mergers may initially be detected as Short Gamma-ray Bursts (SGRBs) or via their gravitational wave emission. Several radio facilities have developed rapid response modes enabling them to trigger on these events and search for this emission. For this paper, we constrain this coherent radio emission using the deepest available constraints for GRB 150424A, which were obtained via a triggered observation with the Murchison Widefield Array. We then expand this analysis to determine the properties of magnetar merger remnants that may be formed via a general population of binary neutron star mergers. Our results demonstrate that many of the potential coherent emission mechanisms that have been proposed for such events can be detected or very tightly constrained by the complementary strategies used by the current generation of low-frequency radio telescopes., Comment: 19 pages, submitted to MNRAS
Published: 2019
Full Text: View/download PDF

30. The FRATS project

Author: Arthur Corstanje, C. J. Law, Antonia Rowlinson, Jörg P. Rachen, Jean-Mathias Grießmeier, S. ter Veen, Heino Falcke, Jochen Eislöffel, P. Zarka, T Winchen, Laura Rossetto, J. E. Enriquez, J. W. Broderick, Antonio Bonardi, M. van den Akker, Jörg R. Hörandel, Anna Nelles, Pim Schellart, A. J. van der Horst, J. van Leeuwen, Rene P. Breton, Stephane Corbel, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Netherlands Institute for Radio Astronomy (ASTRON), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], Jodrell Bank Centre for Astrophysics (JBCA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)
Subjects: 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Pilot survey, general [Pulsars], Astrophysics, Low frequency, Surveys, 01 natural sciences, surveys, pulsars: general, 0103 physical sciences, instrumentation: interferometers, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, Physics, [PHYS]Physics [physics], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], techniques: high angular resolution, Astronomy and Astrophysics, interferometers [Instrumentation], LOFAR, Polarization (waves), high angular resolution [Techniques], Space and Planetary Science, Sky, Radio frequency, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Four-frequency
Abstract: Context. In the previous decade, two new classes of fast radio transients were detected: the Galactic, rotating radio transients (RRATs) and the extragalactic fast radio bursts (FRBs). If the detectable emission of these objects extends to lower radio frequencies, the LOw Frequency ARray (LOFAR) is ideally suited to seek and localize these transients at frequencies of 10–250 MHz. This is due to LOFAR’s sensitivity, diverse beamform capabilities, and transient buffers for the individual elements that allow post-event imaging of events, potentially at arcsecond resolution. Aims. Our aim is to identify and localize pulses at frequencies below 250 MHz and, in the case of nondetections, derive upper limits on the sky and volume rates of FRBs. Methods. A real-time search program for fast radio transients is installed on the LOFAR systems which runs commensally with other observations, and uses the wide incoherent LOFAR beam (11.25 deg2 at 150 MHz). Buffered data from hundreds of dipoles are used to reconstruct the direction and polarization information of the event, and to distinguish between celestial, terrestrial, and instrumental origins. Results. Observations were taken covering either the frequency range 119–151 MHz or in four frequency bands, each of 2 MHz in width, centered at 124, 149, 156, and 185 MHz. A first pilot survey covered a range of dispersion measures (DM) below 120 pc cm−3, focusing on Galactic sources, and resulted in an upper limit on the transient rate at LOFAR frequencies of less than 1500 events per sky per day above a fluency of 1.6 kJy ms for an 8-ms pulse. A second pilot survey covered a range of DMs below 500 pc cm−3, focusing on extragalactic sources to about 1 Gpc, and resulted in an upper limit of 1400 events per sky per day above a fluency of 6.0 kJy ms for an 8-ms pulse. Using a model for the distance-DM relationship, this equates to an upper limit of 134 events per Gpc3 per day.
Published: 2019

31. A VOEvent-based automatic trigger system for the Murchison Widefield Array

Author: D. Kenney, B. W. Meyers, Thomas M. O. Franzen, Brian Crosse, Adam P. Beardsley, G. E. Anderson, K. Steele, Chen Wu, Marcin Sokolowski, D. L. Kaplan, Antonia Rowlinson, Melanie Johnston-Hollitt, Steven Tingay, Randall B. Wayth, David Emrich, D. Pallot, S. E. Tremblay, Cathryn M. Trott, Miguel F. Morales, Mark Walker, Andrew Zic, Paul Hancock, Christene Lynch, Andrew Williams, L. Horsley, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, Virtual observatory, 01 natural sciences, law.invention, Radio telescope, Optics, Pulsar, law, 0103 physical sciences, VOEvent, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, 010308 nuclear & particles physics, business.industry, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Space and Planetary Science, business, Astrophysics - Instrumentation and Methods for Astrophysics, Flare, Superflare
Abstract: The Murchison Widefield Array (MWA) is an electronically steered low frequency ($, 14 pages, 5 figures, accepted for publication in PASA
Published: 2019

32. New methods to constrain the radio transient rate

Author: A. J. van der Horst, Rob Fender, Rene P. Breton, Rudy Wijnands, Stephane Corbel, M. Pietka, Michael Kramer, Benjamin Stappers, D. Carbone, Michael W. Wise, L. H. A. Scheers, P. Zarka, J. van Leeuwen, Y. Cendes, Jean-Mathias Grießmeier, Peter G. Jonker, J. W. Broderick, Adam Stewart, Antonia Rowlinson, Martin Bell, C.J. Law, James Miller-Jones, Ralph A. M. J. Wijers, John D. Swinbank, Jason W. T. Hessels, Jochen Eislöffel, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of Southampton, Oxford Astrophysics, University of Oxford, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Thüringer Landessternwarte Tautenburg (TLS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Radboud University [Nijmegen], Max-Planck-Institut für Radioastronomie (MPIFR), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Curtin University [Perth], Planning and Transport Research Centre (PATREC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), European Project: 247295,EC:FP7:ERC,ERC-2009-AdG,AARTFAAC(2010), High Energy Astrophys. & Astropart. Phys (API, FNWI), Faculty of Science, University of Oxford [Oxford], Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Radboud university [Nijmegen], Database Architectures, Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and ANR-11-IDEX-0005-02/10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2011)
Subjects: radio continuum: general, Astronomy, Pipeline (computing), Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, techniques: image processing, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Limit (music), instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Flux distribution, methods: statistical, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, methods: data analysis, Orders of magnitude (time), Space and Planetary Science, [SDU]Sciences of the Universe [physics], Transient (oscillation), Radio frequency, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the results of a search for radio transients between 115 and 190\,MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 minutes and several months. A total of 151 images were obtained, giving a total survey area of 2275 deg$^2$. We analysed our data using standard LOFAR tools and searched for radio transients using the LOFAR Transients Pipeline (TraP). No credible radio transient candidate has been detected; however, we are able to set upper limits on the surface density of radio transient sources at low radio frequencies. We also show that low-frequency radio surveys are more sensitive to steep-spectrum coherent transient sources than GHz radio surveys. We used two new statistical methods to determine the upper limits on the transient surface density. One is free of assumptions on the flux distribution of the sources, while the other assumes a power-law distribution in flux and sets more stringent constraints on the transient surface density. Both of these methods provide better constraints than the approach used in previous works. The best value for the upper limit we can set for the transient surface density, using the method assuming a power-law flux distribution, is 1.3$\cdot$10$^{-3}$ deg$^{-2}$ for transients brighter than 0.3 Jy with a time-scale of 15 min, at a frequency of 150 MHz. We also calculated for the first time upper limits for the transient surface density for transients of different time-scales. We find that the results can differ by orders of magnitude from previously reported, simplified estimates., 14 pages, 6 figures
Published: 2016

33. Limits on Fast Radio Bursts and other transient sources at 182 MHz using the Murchison Widefield Array

Author: Lincoln J. Greenhill, Randall B. Wayth, Eric R. Morgan, D. Carbone, Daniel A. Mitchell, Divya Oberoi, Thiagaraj Prabu, Melanie Johnston-Hollitt, Gianni Bernardi, K. S. Srivani, Stephen M. Ord, Roger J. Cappallo, David L. Kaplan, Martin Bell, Paul Hancock, Bryna J. Hazelton, Bryan Gaensler, L. Feng, Rachel L. Webster, Christopher L. Williams, N. Udaya Shankar, Simon Johnston, Colin J. Lonsdale, A. R. Offringa, Steven Tingay, Ravi Subrahmanyan, Natasha Hurley-Walker, Antonia Rowlinson, Tara Murphy, Stephen R. McWhirter, Frank H. Briggs, Andrew Williams, Avinash A. Deshpande, Cathryn M. Trott, Miguel F. Morales, Judd D. Bowman, High Energy Astrophys. & Astropart. Phys (API, FNWI), ITA, USA, and AUS
Subjects: Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Population, FOS: Physical sciences, Flux, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 0103 physical sciences, education, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, 010308 nuclear & particles physics, Cosmic distance ladder, Astronomy, Astronomy and Astrophysics, LOFAR, Light curve, 13. Climate action, Space and Planetary Science, Sky, Intergalactic travel, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present a survey for transient and variable sources, on timescales from 28 seconds to $\sim$1 year, using the Murchison Widefield Array (MWA) at 182 MHz. Down to a detection threshold of 0.285 Jy, no transient candidates were identified, making this the most constraining low-frequency survey to date and placing a limit on the surface density of transients of $, Comment: MNRAS Accepted, 17 pages, 10 figures
Published: 2016

34. PySE: Software for extracting sources from radio images

Author: A. J. van der Horst, H. Garsden, John D. Swinbank, Gijs Molenaar, H. Spreeuw, E. Rol, Antonia Rowlinson, D. Carbone, Ralph A. M. J. Wijers, J. W. Broderick, Casey J. Law, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Faculty of Science
Subjects: Computer science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, FOS: Physical sciences, Image processing, ComputerApplications_COMPUTERSINOTHERSYSTEMS, 02 engineering and technology, 01 natural sciences, law.invention, Radio telescope, Telescope, Software, law, Computer graphics (images), 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), computer.programming_language, business.industry, 020206 networking & telecommunications, Astronomy and Astrophysics, LOFAR, Python (programming language), Software package, Computer Science Applications, Space and Planetary Science, business, Astrophysics - Instrumentation and Methods for Astrophysics, computer
Abstract: PySE is a Python software package for finding and measuring sources in radio telescope images. The software was designed to detect sources in the LOFAR telescope images, but can be used with images from other radio telescopes as well. We introduce the LOFAR Telescope, the context within which PySE was developed, the design of PySE, and describe how it is used. Detailed experiments on the validation and testing of PySE are then presented, along with results of performance testing. We discuss some of the current issues with the algorithms implemented in PySE and their inter- action with LOFAR images, concluding with the current status of PySE and its future development., 26 pages, 6 figures
Published: 2018

35. RFI flagging implications for short-duration transients

Author: A. J. van der Horst, D. Carbone, Casey J. Law, Jochen Eislöffel, Jean-Mathias Grießmeier, Ralph A. M. J. Wijers, John D. Swinbank, Martin Bell, Adam Stewart, Y. Cendes, T. Coenen, Folkert Huizinga, M. Pietka, Michael W. Wise, J. W. Broderick, P. Zarka, Peeyush Prasad, Stephane Corbel, Rob Fender, M. Kuniyoshi, Peter G. Jonker, Ben Stappers, Gijs Molenaar, Antonia Rowlinson, A. Alexov, Tim D. Staley, Michael Kramer, High Energy Astrophys. & Astropart. Phys (API, FNWI), API Other Research (FNWI), Faculty of Science, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Netherlands Institute for Radio Astronomy (ASTRON), Oxford Astrophysics, University of Oxford, Sydney Institute for Astronomy (SIfA), The University of Sydney, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Thüringer Landessternwarte Tautenburg (TLS), Department of Physics [Oxford], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Max-Planck-Institut für Radioastronomie (MPIFR), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Oxford [Oxford], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Radboud university [Nijmegen], Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Data stream, Computer science, Astronomy, FOS: Physical sciences, RFI, Automated flagging, 010501 environmental sciences, Low frequency, 01 natural sciences, Signal, transient rates, Electromagnetic interference, Radio telescope, 0103 physical sciences, radio transients, Transient rates, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, Flagging, Astrophysics::Instrumentation and Methods for Astrophysics, food and beverages, Astronomy and Astrophysics, LOFAR, Radio Frequency Interference, Computer Science Applications, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Radio transients, transient rate limits, Space and Planetary Science, Transient rate limits, Transient (oscillation), Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: With their wide fields of view and often relatively long coverage of any position in the sky in imaging survey mode, modern radio telescopes provide a data stream that is naturally suited to searching for rare transients. However, Radio Frequency Interference (RFI) can show up in the data stream in similar ways to such transients, and thus the normal pre-treatment of filtering RFI (flagging) may also remove astrophysical transients from the data stream before imaging. In this paper we investigate how standard flagging affects the detectability of such transients by examining the case of transient detection in an observing mode used for Low Frequency Array (LOFAR; \citep{LOFAR}) surveys. We quantify the fluence range of transients that would be detected, and the reduction of their SNR due to partial flagging. We find that transients with a duration close to the integration sampling time, as well as bright transients with durations on the order of tens of seconds, are completely flagged. For longer transients on the order of several tens of seconds to minutes, the flagging effects are not as severe, although part of the signal is lost. For these transients, we present a modified flagging strategy which mitigates the effect of flagging on transient signals. We also present a script which uses the differences between the two strategies, and known differences between transient RFI and astrophysical transients, to notify the observer when a potential transient is in the data stream., 31 pages, 6 figures, accepted for publication in Astronomy and Computing
Published: 2018

36. The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Author: Tim D. Staley, G. E. Anderson, Clare Rumsey, A. J. van der Horst, J. W. Broderick, Antonia Rowlinson, Ralph A. M. J. Wijers, Rob Fender, David Titterington, Kunal Mooley, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Arcminute Microkelvin Imager, Large array, GRB 130427A, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, Afterglow, law.invention, Radio telescope, Telescope, Space and Planetary Science, law, 0103 physical sciences, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Radio detection
Abstract: We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7 GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to high-energy transients detected by Swift. On receiving a transient alert, AMI can be on-target within two minutes, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (< 1 day) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51 days post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multi-wavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50% over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of >15%, down to ~0.2 mJy/beam. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail sample (all radio-observed GRBs between 1997 - 2011), it is possible ~44 - 56% of Swift GRBs are radio-bright, down to ~0.1 - 0.15 mJy/beam. This increase from the Chandra & Frail rate (~30%) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow., 47 pages (20 of which are catalogue tables), 10 figures, 4 tables, accepted for publication in MNRAS
Published: 2018

37. LOFAR 150-MHz observations of SS 433 and W 50

Author: Sera Markoff, John D. Swinbank, Gijs Molenaar, Rudy Wijnands, James Miller-Jones, Ralph A. M. J. Wijers, J. van Leeuwen, J.-M. Grießmeier, V. I. Kondratiev, Rob Fender, M. Pietka, Benjamin Stappers, S. A. Trushkin, Adam Stewart, J. W. Broderick, A. J. van der Horst, Rene P. Breton, Antonia Rowlinson, G. E. Anderson, Stephane Corbel, D. Carbone, Michael W. Wise, M. Serylak, Heino Falcke, P. Zarka, Jason W. T. Hessels, Martin Bell, Tim D. Staley, Jochen Eislöffel, Katherine M. Blundell, Casey J. Law, Laboratoire AIM, Université Paris Diderot - Paris 7 ( UPD7 ) -Centre d'Etudes de Saclay, Unité Scientifique de la Station de Nançay ( USN ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Centre National de la Recherche Scientifique ( CNRS ) -Université d'Orléans ( UO ) -Institut national des sciences de l'Univers ( INSU - CNRS ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Faculty of Science, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Flux, FOS: Physical sciences, stars: individual: SS 433, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Radio telescope, Telescope, law, 0103 physical sciences, Supernova remnant, 010303 astronomy & astrophysics, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Astrophysics::Galaxy Astrophysics, ISM: supernova remnants, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), ISM: individual objects: W50, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, Galactic plane, Light curve, Astrophysics - Astrophysics of Galaxies, Stars, radio continuum: ISM, ISM: jets and outflows, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], radio continuum: stars
Abstract: We present LOFAR high-band data over the frequency range 115-189 MHz for the X-ray binary SS 433, obtained in an observing campaign from 2013 February - 2014 May. Our results include a deep, wide-field map, allowing a detailed view of the surrounding supernova remnant W 50 at low radio frequencies, as well as a light curve for SS 433 determined from shorter monitoring runs. The complex morphology of W 50 is in excellent agreement with previously published higher-frequency maps; we find additional evidence for a spectral turnover in the eastern wing, potentially due to foreground free-free absorption. Furthermore, SS 433 is tentatively variable at 150 MHz, with both a debiased modulation index of 11 per cent and a $\chi^2$ probability of a flat light curve of $8.2 \times 10^{-3}$. By comparing the LOFAR flux densities with contemporaneous observations carried out at 4800 MHz with the RATAN-600 telescope, we suggest that an observed $\sim$0.5-1 Jy rise in the 150-MHz flux density may correspond to sustained flaring activity over a period of approximately six months at 4800 MHz. However, the increase is too large to be explained with a standard synchrotron bubble model. We also detect a wealth of structure along the nearby Galactic plane, including the most complete detection to date of the radio shell of the candidate supernova remnant G 38.7-1.4. This further demonstrates the potential of supernova remnant studies with the current generation of low-frequency radio telescopes., Comment: 19 pages, 8 figures, 4 tables, accepted for publication in MNRAS
Published: 2018

38. Joint gravitational wave -- gamma-ray burst detection rates in the aftermath of GW170817

Author: David Coward, Kendall Ackley, Eric Howell, Antonia Rowlinson, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, 01 natural sciences, Luminosity, Optics, 0103 physical sciences, Joint (geology), 010303 astronomy & astrophysics, Luminosity function, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), business.industry, 010308 nuclear & particles physics, Gravitational wave, Detector, Astronomy and Astrophysics, Redshift, LIGO, Supernova, Neutron star, 13. Climate action, Space and Planetary Science, Detection rate, business, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The observational follow-up campaign of the gravitational wave (GW) multi-messenger event GW170817/GRB170817A has shown that the prompt $\gamma$-rays are consistent with a relativistic structured jet observed from a wide viewing angle $\gtrsim 20$\deg. We perform Bayesian inference using the data from early and late EM observations to determine the jet profile of GRB170817A assuming a structured jet model. We use the geometric dependence on the burst luminosity to produce a short duration gamma-ray burst (sGRB) efficiency function with redshift, which folded in with binary neutron star detection rate, allows us to estimate the future joint GW/sGRB detection rates for LIGO and Virgo detectors. We show that, if the jet structured profile of GRB170817A is a relatively common feature of sGRBs, then there is a realistic probability of another off-axis coincident detection during the third aLIGO/Virgo observing run (O3). We also find that up to 4 yr$^{-1}$ joint events may be observed during the advanced LIGO run at design sensitivity and up to 10 yr$^{-1}$ by the upgraded advanced LIGO configuration A+. We show that the detection efficiencies for wide-angled sGRB emissions will be limited by GRB satellites as the GW detection range increases through proposed upgrades. Therefore, although the number of coincident detections will increase with GW detector sensitivity, the relative proportion of detected binary neutron stars with $\gamma$-ray counterparts will decrease; 11\% for O3 down to 2\% during A+., Comment: Updated to final accepted MNRAS version
Published: 2018
Full Text: View/download PDF

39. Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR

Author: M. C. Toribio, B. Ciardi, J. M. Anderson, Eduard P. Kontar, Karl-Ludwig Klein, Charlotte Sobey, Jochen Eislöffel, Marian Soida, Marco Iacobelli, P. Zarka, A. P. Rouillard, R. Blaauw, A. G. Polatidis, R. J. van Weeren, Mario M. Bisi, A. W. Gunst, E. de Geus, Mark J. Bentum, Oleg Smirnov, Henk Mulder, R. Pizzo, Aris Karastergiou, F. Breitling, Pietro Zucca, Jörg R. Hörandel, Hanna Rothkaehl, Peter T. Gallagher, H. Munk, Bartosz Dabrowski, Martin Bell, Olaf Wucknitz, Anna Nelles, R. Vermeulen, Jean-Mathias Grießmeier, Marcus Brüggen, Ashish Asgekar, V. N. Pandey, H. Paas, Jasmina Magdalenic, Richard Fallows, Matthias Hoeft, Christian Vocks, Philip Best, J. W. Broderick, Harvey Butcher, J. Sluman, D. McKay-Bukowski, E. Juette, M. A. Garrett, Andrzej Krankowski, Satyendra Thoudam, Antonia Rowlinson, R. Pekal, S. Duscha, Eoin P. Carley, Adam T. Deller, Dominik J. Schwarz, Wolfgang Reich, J. van Leeuwen, Emanuela Orru, Diana E. Morosan, Aleksandar Shulevski, Gottfried Mann, George Heald, W. N. Brouw, Netherlands Institute for Radio Astronomy (ASTRON), Trinity College Dublin, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Leibniz-Institut für Astrophysik Potsdam (AIP), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk (PAN), Space Radio-Diagnostic Research Center [Olsztyn], University of Warmia and Mazury [Olsztyn], School of Physics and Astronomy [Southampton], University of Southampton, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Universität Hamburg (UHH), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Thüringer Landessternwarte Tautenburg (TLS), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Radboud university [Nijmegen], Ruhr-Universität Bochum [Bochum], Oxford Astrophysics, University of Oxford [Oxford], University of Tromsø (UiT), Max-Planck-Institut für Radioastronomie (MPIFR), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Center for Wireless Technology Eindhoven, Electromagnetics, EM for Radio Science Lab, High Energy Astrophys. & Astropart. Phys (API, FNWI), Astronomy, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Universiteit Leiden, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], University of Oxford, ANR-17-CE31-0006,COROSHOCK,EVALUER LE ROLE DU CHOC COMME ACCELERATEUR DE PARTICULES SOLAIRES(2017), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)
Subjects: 010504 meteorology & atmospheric sciences, corona [Sun], Sun: coronal mass ejections (CMEs), Astronomy, Astrophysics::High Energy Astrophysical Phenomena, WAVES, Interplanetary medium, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Computer Science::Digital Libraries, 01 natural sciences, VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Astrofysikk, astronomi: 438, 0103 physical sciences, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, SUN-EARTH CONNECTION, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Science & Technology, Sun: radio radiation, ORIGIN, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], radio radiation [Sun], Sun: corona, Astrophysics::Instrumentation and Methods for Astrophysics, TRANSIENTS, Astronomy and Astrophysics, LOFAR, Corona, Physics::History of Physics, coronal mass ejections (CMEs) [Sun], VDP::Mathematics and natural science: 400::Physics: 430::Astrophysics, astronomy: 438, CORONAL MASS EJECTIONS, Radio propagation, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Physical Sciences, FLARES, Physics::Space Physics, X-RAY, Large Angle and Spectrometric Coronagraph, EMISSION, Heliosphere, Radio wave
Abstract: Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with CMEs and reach speeds higher than the local magnetosonic speed. Radio imaging of decameter wavelengths (20-90 MHz) is now possible with LOFAR, opening a new radio window in which to study coronal shocks that leave the inner solar corona and enter the interplanetary medium and to understand their association with CMEs. To this end, we study a coronal shock associated with a CME and type II radio burst to determine the locations at which the radio emission is generated, and we investigate the origin of the band-splitting phenomenon., Comment: 7 Figures, 9 Pages
Published: 2018

40. LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies

Author: Adam Stewart, Jamie Farnes, B. Adebahr, R. J. van Weeren, M. Pandey-Pommier, Joseph R. Callingham, C. J. Riseley, Antonia Rowlinson, Aleksandar Shulevski, Volker Heesen, K. Sendlinger, Huub Röttgering, George Heald, A. J. van der Horst, Emanuela Orru, P. Surma, Anna M. M. Scaife, R.-J. Dettmar, M. Curyło, Rene P. Breton, D. D. Mulcahy, J. Piotrowska, Martin J. Hardcastle, Rainer Beck, S. S. Sridhar, Rosita Paladino, R. Pizzo, Marco Iacobelli, A. O. Clarke, Błażej Nikiel-Wroczyński, W. Jurusik, J. W. Broderick, V. Vacca, Krzysztof T. Chyzy, G. Gürkan, Natalia Nowak, V. N. Pandey, John Conway, High Energy Astrophys. & Astropart. Phys (API, FNWI), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, Astrophysics, galaxies [Radio continuum], Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, 01 natural sciences, Flattening, Spectral line, statistics [Galaxies], 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, galaxies: statistics, Astrophysics::Galaxy Astrophysics, media_common, Physics, radio continuum: galaxies, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, LOFAR, Viewing angle, evolution [Galaxies], Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), galaxies: evolution
Abstract: The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take advantage of the LOFAR Multifrequency Snapshot Sky Survey (MSSS) to investigate such spectra for a large sample of nearby star-forming galaxies. Using the measured 150MHz flux densities from the LOFAR MSSS survey and literature flux densities at various frequencies we have obtained integrated radio spectra for 106 galaxies. The spectra are explained through the use of a three-dimensional model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Spectra of our galaxies are generally flatter at lower compared to higher frequencies but as there is no tendency for the highly inclined galaxies to have more flattened low-frequency spectra, we argue that the observed flattening is not due to thermal absorption, contradicting the suggestion of Israel & Mahoney (1990). According to our modelled radio maps for M51-like galaxies, the free-free absorption effects can be seen only below 30MHz and in the global spectra just below 20MHz, while in the spectra of starburst galaxies, like M82, the flattening due to absorption is instead visible up to higher frequencies of about 150MHz. Locally, within galactic disks, the absorption effects are distinctly visible in M51-like galaxies as spectral flattening around 100-200MHz in the face-on objects, and as turnovers in the edge-on ones, while in M82-like galaxies there are strong turnovers at frequencies above 700MHz, regardless of viewing angle. Our modelling suggests that the weak spectral flattening observed in the nearby galaxies studied here results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects., Accepted for publication in Astronomy and Astrophysics (corrected typo in the title)
Published: 2018

41. LOFAR discovery of a quiet emission mode in PSR B0823+26

Author: F. Breitling, Gottfried Mann, R. Pizzo, John D. Anderson, Cees Bassa, Sera Markoff, Rene P. Breton, Ashish Asgekar, Charlotte Sobey, E. Jütte, George Heald, Heino Falcke, P. Maat, M. J. Norden, M. A. Garrett, Jean-Mathias Grießmeier, Ph. Zarka, Rebecca McFadden, H. Paas, Ben Stappers, E. de Geus, Sarod Yatawatta, V. I. Kondratiev, D. D. Mulcahy, J. van Leeuwen, S. ter Veen, M. Pilia, M. Pandey-Pommier, Ralph A. M. J. Wijers, A. W. Gunst, J. Sluman, Olaf Wucknitz, H. J. A. Röttgering, Philip Best, Christian Vocks, D. McKay-Bukowski, Michel Tagger, D. Carbone, A. Alexov, Andrew Lyne, Antonia Rowlinson, A. Noutsos, Adam Stewart, Chiara Ferrari, T. E. Hassall, Evan Keane, Patrick Weltevrede, Jason W. T. Hessels, Satyendra Thoudam, S. Duscha, M. Serylak, A. van Duin, G. Pietka, Laura Birzan, Jochen Eislöffel, J. P. Hamaker, Wilfred Frieswijk, C. Toribio, Michael Kramer, D. A. Rafferty, A. G. Polatidis, Arthur Corstanje, A. Nelles, John D. Swinbank, Y. Tang, Anna M. M. Scaife, Martin Bell, N. J. Young, V. N. Pandey, Gerard H. Kuper, Cyril Tasse, J. W. Broderick, H. Munk, John McKean, Marcus Brüggen, Matthias Steinmetz, Annalisa Bonafede, A. Renting, Richard Fallows, R. Vermeulen, Mark J. Bentum, Matthias Hoeft, M. de Vos, Aris Karastergiou, Michael W. Wise, Gianni Bernardi, Jörg R. Hörandel, Rob Fender, Oleg Smirnov, Emanuela Orru, Dominik J. Schwarz, I. M. Avruch, Anna V. Bilous, R. J. van Weeren, Sobey, C., Young, N.J., Hessels, J.W.T., Weltevrede, P., Noutsos, A., Stappers, B.W., Kramer, M., Bassa, C., Lyne, A.G., Kondratiev V.I., null, Hassall, T.E., Keane, E.F., Bilous, A.V., Breton, R.P., Grießmeier, J.M., Karastergiou, A., Pilia, M., Serylak, M., Ter Veen, S., Van Leeuwen, J., Alexov, A., Anderson, J., Asgekar, A., Avruch, I.M., Bell, M.E., Bentum, M.J., Bernardi, G., Best, P., Bĭrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Corstanje, A., Carbone, D., De Geus, E., De Vos, M., Van Duin, A., Duscha, S., Eislöffel, J., Falcke, H., Fallows, R.A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., Gunst, A.W., Hamaker, J.P., Heald, G., Hoeft, M., Hörandel, J., Jütte, E., Kuper, G., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., McKean, J.P., Mulcahy, D.D., Munk, H., Nelles, A., Norden, M.J., Orrù, E., Paas, H., Pandey-Pommier, M., Pandey, V.N., Pietka, G., Pizzo, R., Polatidis, A.G., Rafferty, D., Renting, A., Röttgering, H., Rowlinson, A., Scaife, A.M.M., Schwarz, D., Sluman, J., Smirnov, O., Steinmetz, M., Stewart, A., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Thoudam, S., Toribio, C., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wijers, R.A.M.J., Wise, M.W., Wucknitz, O., Yatawatta, S., Zarka, P., Max-Planck-Institut für Radioastronomie (MPIFR), University of Minnesota [Twin Cities] (UMN), University of Minnesota System, University of Amsterdam [Amsterdam] (UvA), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Cornell University [New York], Netherlands Institute for Radio Astronomy (ASTRON), Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Rhodes University, Grahamstown, Oxford Astrophysics, University of Oxford, Institute for Mathematics Applied to Geoscience, National Center for Atmospheric Research [Boulder] (NCAR), SRON Netherlands Institute for Space Research (SRON), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Edinburgh, Leiden Observatory [Leiden], Universiteit Leiden, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), University of Southampton, Medstar Research Institute, Thüringer Landessternwarte Tautenburg (TLS), Institute of Mathematical and Physical Sciences, Département de Géologie, Université de Montréal (UdeM), University Bochum, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Oulu, Center for Information Technology CIT, Université de Groningen, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), National Radio Astronomy Observatory [Charlottesville] (NRAO), National Radio Astronomy Observatory (NRAO), Department of Astronomy and Astrophysics [PennState], Pennsylvania State University (Penn State), Penn State System-Penn State System, School of Physics and Astronomy [Southampton], Interactions Son Musique Mouvement, Sciences et Technologies de la Musique et du Son (STMS), Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche et Coordination Acoustique/Musique (IRCAM)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Université Paris-Sud - Paris 11 (UP11), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), SKA South Africa, Ska South Africa, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, We would like to thank R. Karuppusamy for his help with the Effelsberg observations. CF acknowledges financial support by the Agence Nationale de la Recherche through grant ANR-09-JCJC-0001-01., European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), ITA, GBR, FRA, DEU, NLD, Radboud university [Nijmegen], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), University of Oxford [Oxford], Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universiteit Leiden [Leiden], École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Harvard University [Cambridge]-Smithsonian Institution, Astronomy, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: stars, PSR B0823+26-radio telescopes, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, FOS: Physical sciences, neutron- pulsars, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, neutron [stars], Pulsar, Millisecond pulsar, Pulsars: individual: PSR B0823+26, individual, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Astroparticle physics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Stars: neutron, Stars, Neutron star, Astrophysics - Solar and Stellar Astrophysics, magnetosphere-pulsars, [SDU]Sciences of the Universe [physics], Space and Planetary Science, QUIET, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics - High Energy Astrophysical Phenomena, individual: PSR B0823+26 [pulsars]
Abstract: PSR B0823+26, a 0.53-s radio pulsar, displays a host of emission phenomena over timescales of seconds to (at least) hours, including nulling, subpulse drifting, and mode-changing. Studying pulsars like PSR B0823+26 provides further insight into the relationship between these various emission phenomena and what they might teach us about pulsar magnetospheres. Here we report on the LOFAR discovery that PSR B0823+26 has a weak and sporadically emitting 'quiet' (Q) emission mode that is over 100 times weaker (on average) and has a nulling fraction forty-times greater than that of the more regularly-emitting 'bright' (B) mode. Previously, the pulsar has been undetected in the Q-mode, and was assumed to be nulling continuously. PSR B0823+26 shows a further decrease in average flux just before the transition into the B-mode, and perhaps truly turns off completely at these times. Furthermore, simultaneous observations taken with the LOFAR, Westerbork, Lovell, and Effelsberg telescopes between 110 MHz and 2.7 GHz demonstrate that the transition between the Q-mode and B-mode occurs within one single rotation of the neutron star, and that it is concurrent across the range of frequencies observed., Comment: 15 pages, 8 figures, 2 tables, accepted for publication in MNRAS
Published: 2015

42. The LOFAR Transients Pipeline

Author: Rudy Wijnands, Hugh Garsden, Benjamin Stappers, Casey J. Law, Jochen Eislöffel, Heino Falcke, E. Rol, John D. Swinbank, Adam Stewart, Rene P. Breton, Jason W. T. Hessels, Rob Fender, Philippe Zarka, Stephane Corbel, D. Carbone, Bart Scheers, Martin Bell, Y. Cendes, J. W. Broderick, Antonia Rowlinson, Ralph A. M. J. Wijers, Tim D. Staley, Jean-Mathias Grießmeier, Michael W. Wise, Alexander J. van der Horst, Gijs Molenaar, H. Spreeuw, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Department of Astrophysical Sciences [Princeton], Princeton University, Oxford Astrophysics, University of Oxford [Oxford], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Universität Hamburg (UHH), University of Southampton, Berkeley Radio Astronomy Laboratory (RAL), Department of Astronomy [Berkeley], University of California [Berkeley], University of California-University of California-University of California [Berkeley], University of California-University of California, Netherlands Institute for Radio Astronomy (ASTRON), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Thüringer Landessternwarte Tautenburg (TLS), Université Grenoble Alpes - UFR Médecine (UGA UFRM), Université Grenoble Alpes (UGA), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), ANR-10-LABX-0023,Labex UnivEarthS, ANR-11-IDEX-0005-02/11-IDEX-0005,USPC,USPC(2011), European Project: 247295,EC:FP7:ERC,ERC-2009-AdG,AARTFAAC(2010), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), University of Oxford, University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC)-University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics (JBCA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2010), ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), Database Architectures, Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Astronomy, Real-time computing, Population, FOS: Physical sciences, Techniques: image processing, Astronomical survey, 01 natural sciences, Trap (computing), Methods: data analysis, 0103 physical sciences, education, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Remote sensing, Physics, education.field_of_study, 010308 nuclear & particles physics, business.industry, Astronomical transients, Astronomical databases, Astronomy and Astrophysics, LOFAR, Time domain astrophysics, Automation, Pipeline (software), Computer Science Applications, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Identification (information), Space and Planetary Science, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, business, Astrophysics - Instrumentation and Methods for Astrophysics, Radio astronomy
Abstract: Current and future astronomical survey facilities provide a remarkably rich opportunity for transient astronomy, combining unprecedented fields of view with high sensitivity and the ability to access previously unexplored wavelength regimes. This is particularly true of LOFAR, a recently-commissioned, low-frequency radio interferometer, based in the Netherlands and with stations across Europe. The identification of and response to transients is one of LOFAR's key science goals. However, the large data volumes which LOFAR produces, combined with the scientific requirement for rapid response, make automation essential. To support this, we have developed the LOFAR Transients Pipeline, or TraP. The TraP ingests multi-frequency image data from LOFAR or other instruments and searches it for transients and variables, providing automatic alerts of significant detections and populating a lightcurve database for further analysis by astronomers. Here, we discuss the scientific goals of the TraP and how it has been designed to meet them. We describe its implementation, including both the algorithms adopted to maximize performance as well as the development methodology used to ensure it is robust and reliable, particularly in the presence of artefacts typical of radio astronomy imaging. Finally, we report on a series of tests of the pipeline carried out using simulated LOFAR observations with a known population of transients., Comment: 30 pages, 11 figures; Accepted for publication in Astronomy & Computing; Code at https://github.com/transientskp/tkp
Published: 2015

43. A new analysis of the short-duration, hard-spectrum GRB 051103, a possible extragalactic soft gamma repeater giant flare

Author: D. Bersier, R. Vanderspek, Yujin E. Nakagawa, James E. Rhoads, Masanori Ohno, H. A. Krimm, A. S. Kozyrev, Daniel A. Perley, William V. Boynton, I. G. Mitrofanov, Antonia Rowlinson, K. Hurley, C. Fellows, J. L. Atteia, A. J. Levan, N. Gehrels, A. B. Sanin, George R. Ricker, A. S. Fruchter, Robert C. Duncan, M. L. Litvak, K. Harshmann, A. Rau, T. Cline, E. Rol, Eric C. Bellm, K. Wiersema, Jj Kavelaars, Nial R. Tanvir, P. T. O'Brien, Kazutaka Yamaoka, Dmitry Golovin, W. Hajdas, D. M. Palmer, David M. Smith, Claudia Wigger, A. von Kienlin, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Faculty of Science
Subjects: Physics, media_common.quotation_subject, Soft gamma repeater, Astronomy and Astrophysics, Astrophysics, Magnetar, Galaxy, Afterglow, law.invention, Space and Planetary Science, Sky, law, QD, Gamma-ray burst, Supernova remnant, QC, QB, media_common, Flare
Abstract: GRB 051103 is considered to be a candidate soft gamma repeater (SGR) extragalactic giant magnetar flare by virtue of its proximity on the sky to M81/M82, as well as its time history, localization, and energy spectrum. We have derived a refined interplanetary network localization for this burst which reduces the size of the error box by over a factor of two. We examine its time history for evidence of a periodic component, which would be one signature of an SGR giant flare, and conclude that this component is neither detected nor detectable under reasonable assumptions. We analyze the time-resolved energy spectra of this event with improved time- and energy resolution, and conclude that although the spectrum is very hard, its temporal evolution at late times cannot be determined, which further complicates the giant flare association. We also present new optical observations reaching limiting magnitudes of R > 24.5, about 4 magnitudes deeper than previously reported. In tandem with serendipitous observations of M81 taken immediately before and one month after the burst, these place strong constraints on any rapidly variable sources in the region of the refined error ellipse proximate to M81. We do not find any convincing afterglow candidates from either background galaxies or sources in M81, although within the refined error region we do locate two UV bright star forming regions which may host SGRs. A supernova remnant (SNR) within the error ellipse could provide further support for an SGR giant flare association, but we were unable to identify any SNR within the error ellipse. These data still do not allow strong constraints on the nature of the GRB 051103 progenitor, and suggest that candidate extragalactic SGR giant flares will be difficult, although not impossible, to confirm.
Published: 2017

44. The Braking Index of Millisecond Magnetars

Author: Antonia Rowlinson, Kostas Glampedakis, Cristiano Leris, Paul D. Lasky, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Millisecond, Index (economics), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Magnetar, 01 natural sciences, Neutron star, Space and Planetary Science, 0103 physical sciences, Gamma-ray burst, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract: We make the first measurement of the braking index $n$ of two putative millisecond magnetars born in short gamma-ray bursts. We measure $n=2.9\pm0.1$ and $n=2.6\pm0.1$ for millisecond magnetars born in GRB 130603B and GRB 140903A respectively. The neutron star born in GRB 130603B has the only known braking index consistent with the fiducial $n=3$ value. This value is ruled out with 99.95\% confidence for GRB 140903A. We discuss possible causes of $n, ApJL
Published: 2017

45. LOFAR MSSS: Discovery of a 2.56 Mpc giant radio galaxy associated with a disturbed galaxy group

Author: Michael W. Wise, Leah K. Morabito, Jeremy J. Harwood, D. Carbone, Emanuela Orru, T. M. Cantwell, Judith H. Croston, Marisa Brienza, G. Kokotanekov, Rosita Paladino, George Heald, D. D. Mulcahy, A. O. Clarke, Annalisa Bonafede, A. Horneffer, Luke Pratley, Huub Röttgering, Martin J. Hardcastle, Adam Stewart, S. S. Sridhar, Cyril Tasse, Marco Iacobelli, R. Pizzo, J. W. Broderick, Jamie Farnes, A. J. van der Horst, K. Sendlinger, Anna M. M. Scaife, Rene P. Breton, J. Sabater, Volker Heesen, Thomas H. Jarrett, W. Jurusik, M. Pietka, Justin D. Bray, S. van Velzen, Błażej Nikiel-Wroczyński, John McKean, M. Pandey-Pommier, Antonia Rowlinson, R. J. van Weeren, C. J. Riseley, Aleksandar Shulevski, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon ( CRAL ), École normale supérieure - Lyon ( ENS Lyon ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Galaxies, Etoiles, Physique, Instrumentation ( GEPI ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Astronomy, Kapteyn Astronomical Institute, Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: SELECTION, Active galactic nucleus, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Stellar mass, Radio galaxy, Astronomy, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, UNIVERSE, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, galaxies [infrared], infrared: galaxies, surveys, galaxies: groups: general, Galaxy group, 0103 physical sciences, WISE, galaxies: interactions, FIELD, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, radio continuum: galaxies, 010308 nuclear & particles physics, Star formation, groups: general [galaxies], interactions [galaxies], supermassive black holes [quasars], quasars: supermassive black holes, Velocity dispersion, Astronomy and Astrophysics, LOFAR, ATLAS, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies [radio continuum], EVOLUTION, I. SURVEY DESCRIPTION, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), ALL-SKY SURVEY, SDSS-III, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, CLUSTERS, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We report on the discovery in the LOFAR Multifrequency Snapshot Sky Survey (MSSS) of a giant radio galaxy (GRG) with a projected size of $2.56 \pm 0.07$ Mpc projected on the sky. It is associated with the galaxy triplet UGC 9555, within which one is identified as a broad-line galaxy in the Sloan Digital Sky Survey (SDSS) at a redshift of $0.05453 \pm 1 \times 10^{-5} $, and with a velocity dispersion of $215.86 \pm 6.34$ km/s. From archival radio observations we see that this galaxy hosts a compact flat-spectrum radio source, and we conclude that it is the active galactic nucleus (AGN) responsible for generating the radio lobes. The radio luminosity distribution of the jets, and the broad-line classification of the host AGN, indicate this GRG is orientated well out of the plane of the sky, making its physical size one of the largest known for any GRG. Analysis of the infrared data suggests that the host is a lenticular type galaxy with a large stellar mass ($\log~\mathrm{M}/\mathrm{M}_\odot = 11.56 \pm 0.12$), and a moderate star formation rate ($1.2 \pm 0.3~\mathrm{M}_\odot/\mathrm{year}$). Spatially smoothing the SDSS images shows the system around UGC 9555 to be significantly disturbed, with a prominent extension to the south-east. Overall, the evidence suggests this host galaxy has undergone one or more recent moderate merger events and is also experiencing tidal interactions with surrounding galaxies, which have caused the star formation and provided the supply of gas to trigger and fuel the Mpc-scale radio lobes., Compressed for arXiv, see journal for full resolution images
Published: 2017

46. The Emergence of a Lanthanide-rich Kilonova Following the Merger of Two Neutron Stars

Author: Ryan Wollaeger, Antonia Rowlinson, C. C. Thoene, Ilya Mandel, Johan P. U. Fynbo, Krzysztof Ulaczyk, Stefano Covino, Valerio D'Elia, J. D. Lyman, D. Malesani, Oleg Korobkin, T. Kangas, P. D'Avanzo, Richard G. McMahon, Darach Watson, E. Rol, A. de Ugarte Postigo, A. S. Fruchter, Zach Cano, Eliana Palazzi, Markus Rabus, Mike Irwin, J. P. Osborne, Patrick J. Sutton, G. Hodosan, Daniel A. Perley, A. Melandri, Jochen Greiner, Andrew J. Levan, P. A. Evans, Jens Hjorth, U. G. Jørgensen, D. A. Kann, R. Figuera Jaimes, Christopher J. Fontes, Klaas Wiersema, Carlos González-Fernández, Elena Pian, B. P. Gompertz, Chris M. Copperwheat, S. Piranomonte, Ralph A. M. J. Wijers, Stephen Fairhurst, Steve Schulze, P. T. O'Brien, Chris L. Fryer, Stephan Rosswog, Nial R. Tanvir, Wesley Even, Danny Steeghs, S. Rosetti, Yuri I. Fujii, Pall Jakobsson, B. Milvang-Jensen, European Research Council, Ministerio de Economía, Industria y Competitividad (España), Swedish Research Council, High Energy Astrophys. & Astropart. Phys (API, FNWI), Raunvísindastofnun (HÍ), Science Institute (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland, Tanvir, NR [0000-0003-3274-6336], Korobkin, O [0000-0003-4156-5342], Hjorth, J [0000-0002-4571-2306], Fryer, CL [0000-0003-2624-0056], Milvang-Jensen, B [0000-0002-2281-2785], Cano, Z [0000-0001-9509-3825], Covino, S [0000-0001-9078-5507], Even, WP [0000-0002-5412-3618], Fairhurst, S [0000-0001-8480-1961], Fujii, YI [0000-0002-3648-0507], Irwin, MJ [0000-0002-2191-9038], Kann, DA [0000-0003-2902-3583], Malesani, D [0000-0002-7517-326X], McMahon, RG [0000-0001-8447-8869], Perley, DA [0000-0001-8472-1996], Pian, E [0000-0001-8646-4858], Rabus, M [0000-0003-2935-7196], Watson, D [0000-0002-4465-8264], Wiersema, K [0000-0002-9133-7957], Apollo - University of Cambridge Repository, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science
Subjects: Nuclear reactions, nucleosynthesis, abundances, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Kilonova, 01 natural sciences, 7. Clean energy, Gravitational waves, stars: neutron, Nucleosynthesis, abundances, Nucleosynthesis, 0103 physical sciences, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, Abundances, Ejecta, 010303 astronomy & astrophysics, QC, nuclear reactions, Astrophysics::Galaxy Astrophysics, QB, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Gravitational wave, abundances, nucleosynthesis, Astronomy and Astrophysics, neutron [Stars], 3rd-DAS, Stjarneðlisfræði, LIGO, Hubblessjónaukinn, Neutron star, QC Physics, gravitational waves, Space and Planetary Science, Stjörnufræði, Nuclear reactions, Astrophysics - High Energy Astrophysical Phenomena, Radioactive decay, Fermi Gamma-ray Space Telescope
Abstract: Tanvir, N.R. et. al., We report the discovery and monitoring of the near-infrared counterpart (AT2017gfo) of a binary neutron-star merger event detected as a gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) and as a short gamma-ray burst by Fermi Gamma-ray Burst Monitor (GBM) and Integral SPI-ACS (GRB 170817A). The evolution of the transient light is consistent with predictions for the behavior of a >kilonova/macronova> powered by the radioactive decay of massive neutron-rich nuclides created via r-process nucleosynthesis in the neutron-star ejecta. In particular, evidence for this scenario is found from broad features seen in Hubble Space Telescope infrared spectroscopy, similar to those predicted for lanthanide-dominated ejecta, and the much slower evolution in the near-infrared k-band compared to the optical. This indicates that the late-time light is dominated by high-opacity lanthanide-rich ejecta, suggesting nucleosynthesis to the third r-process peak (atomic masses A ≈ 195). This discovery confirms that neutron-star mergers produce kilo-/macronovae and that they are at least a major - if not the dominant - site of rapid neutron capture nucleosynthesis in the universe., A.J.L., D.S., and J.D.L. acknowledge support from STFC via grant ST/P000495/1. N.R.T. and A.J.L. have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement No. 725246, TEDE, Levan). Ad.U.P., C.T., Z.C., and D.A.K. acknowledge support from the Spanish project AYA 2014-58381-P. Z.C. also acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669, and D.A.K. from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. J.H. is supported by a VILLUM FONDEN Investigator grant (project number 16599). P.D.A., S.C., and A.M. acknowledge support from the ASI grant I/004/11/3. S.R. has been supported by the Swedish Research Council (VR) under grant No. 2016-03657_3, by the Swedish National Space Board under grant No. Dnr. 107/16, and by the research environment grant >Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT)> funded by the Swedish Research council (VR) under Dnr 2016-06012.
Published: 2017

47. A polarized fast radio burst at low Galactic latitude

Author: M. de Jong, Michael Punch, Mansi M. Kasliwal, T. A. Pritchard, S. Galatà, K. Egberts, S. Loucatos, C. Tönnis, S. Öttl, G. Pelletier, Ivan Felis, Mitchell B. Mickaliger, Jacek Niemiec, G. Cologna, Robert Wagner, A. Gleixner, C. Racca, P. J. Meintjes, Thomas Lohse, Jamie Farnes, Olaf Reimer, F. Ait Benkhali, L. O'c. Drury, P. de Wilt, R. Chalme-Calvet, I. Salvadori, Kay Graf, Karel Melis, A. Vizzoca, I. El Bojaddaini, G. Heinzelmann, C. B. Rulten, Bruny Baret, Heinrich J. Völk, Manami Sasaki, S. Schwemmer, Q. Piel, Andrea Santangelo, Thomas Vuillaume, Guillaume Dubus, A. Jacholkowska, Simon Johnston, J. Chevalier, Julien Lefaucheur, M. Renaud, K. Dutson, F. Spies, D. Dornic, C. Farnier, A. Trovato, E. Leser, Tanya Edwards, Jean-Pierre Macquart, L. Tibaldo, Thomas Murach, C. Lachaud, A. Marinelli, I. D. Davids, Ramin Marx, M. Panter, U. Katz, Silvia Celli, Timothée Grégoire, D. Kiessling, Antoine Kouchner, Marco Padovani, Matthias Kadler, Francois Brun, A. Ivascenko, E. D. Barr, C. W. James, Daniela Hadasch, C. Perrina, Maria Tselengidou, G. Hermann, Regis Terrier, D. Klochkov, Johan Bregeon, W. Kluzniak, M. Kieffer, P. Vincent, Y. Cui, S. Bernhard, L. Stawarz, A. Ziegler, M.C. Bouwhuis, C. Romoli, Dieter Horns, Mateusz Janiak, B. van Soelen, B. Rudak, T. Michael, Nachiketa Chakraborty, Caterina Tiburzi, N. Zywucka, Alison Mitchell, B. Degrange, Santiago Pita, R. Blackwell, Reinhard Schlickeiser, I. Kreykenbohm, Annarita Margiotta, Jutta Schnabel, M. Jingo, R. J. White, Thomas Eberl, H. Laffon, M. Lotze, Christo Venter, Tommaso Chiarusi, M. Anghinolfi, Maura McLaughlin, Zorawar Wadiasingh, B. Condon, D. A. Sanchez, M. Mayer, V. Lefranc, H. Abdalla, M. A. Kastendieck, S. Bourret, G. Vasileiadis, Iryna Lypova, Yvonne Becherini, G. Illuminati, Clemens Hoischen, A. A. Zdziarski, S. Geisselsoder, I. Shilon, E. O. Angüner, Domenico Tiziani, K. Kosack, Konrad Bernlöhr, A. Enzenhöfer, R. Moderski, V. S. Dhillon, Evan Keane, G. Lamanna, Riaan Steenkamp, Matthew Bailes, M. Füssling, A. Zech, V. Van Elewyck, M. Taiuti, J. Decock, Ullrich Schwanke, Monica Barnard, D. Zaborov, O. Kalekin, M. Circella, Y. A. Gallant, N. D. R. Bhat, A. Creusot, Victor Zabalza, Th. Stolarczyk, B. Vallage, N. Maxted, Dominique Lefèvre, L. Dirson, E. Petroff, D. Jankowsky, M.-H. Grondin, C. Perennes, Markus Böttcher, E. Nezri, A. G. Akhperjanian, Maria Haupt, Jürgen Brunner, G. Pühlhofer, S. Klepser, A. Wörnlein, Denis Wouters, Armin Rest, A. Possenti, R. C. G. Chaves, C. Mueller, P. Coyle, F. Zefi, Poonam Chandra, F. Niederwanger, R. D. Parsons, Anne Deschamps, T. Seitz, Daniele Vivolo, D. J. Champion, C. Sieger, J. Dyks, F. Schüssler, L. Caramete, A. Reimer, Felix Spanier, Dominik Elsässer, H. van Haren, S. R. Bernard, T. Garrigoux, K. Morå, I. Di Palma, L. K. Hardy, David Salek, E. Moulin, Justine Devin, Michal Ostrowski, Tomasz Bulik, J.-P. Lenain, Luigi Antonio Fusco, Thomas Tavernier, Matteo Sanguineti, A. Sánchez-Losa, M. Capasso, S. J. Fegan, A. Djannati-Ataï, G. Riccobene, Gianluca Giavitto, Benjamin Stappers, Gilles Maurin, I. Oya, L. Quinn, Axel Donath, Jacco Vink, A. W. Chen, J. Zúñiga, A. S. Seyffert, R. Miller, Pierre-Henri Aubert, Nu. Komin, Sabrina Casanova, Andrew M. Taylor, Jörn Wilms, M. Kreter, Mark Sullivan, Michael Kramer, S. Krakau, V. Sahakian, R. Bruijn, Andreas Quirrenbach, J-J. Aubert, R. Borrnuth, M. Saldaña, Aion Viana, C. Mariaud, Joao A B Coelho, J. P. Lees, P. Migliozzi, D. J. van der Walt, M. Settimo, C. Vallée, Christian Stegmann, Stefan Wagner, Gisela Anton, Bruno Khelifi, Jan Conrad, M. Marcelin, V. Giordano, M. Lorentz, M. Kraus, D. Kerszberg, T. Avgitas, Rachel Simoni, Helen Poon, J.A. Martínez-Mora, Alexis Coleiro, Antonia Rowlinson, S. Raab, Stefan Funk, Alicja Wierzcholska, B. Peyaud, Yasunobu Uchiyama, R. J. Tuffs, L. Mohrmann, Juan José Hernández-Rey, T. Jogler, D.A. Prokhorov, Michel André, Frank M. Rieger, J.D. Zornoza, A. Schulz, T. Pradier, S. Wagner, A. Abramowski, R. Mele, S. Rosier-Lees, G. Spengler, Yann Hello, J. Lau, C. van Rensburg, M. Holler, R. Coniglione, Arnauld Albert, Emanuele Leonora, A. Balzer, Michael Zacharias, M. Mohamed, Yahya Tayalati, J. Carr, I. Jung-Richardt, A. Mathieu, A. Fiasson, Roberta Zanin, P. Willmann, Hervé Glotin, K. Geyer, K. Roensch, Michael Backes, Alexandre Marcowith, J. King, J. Hofestädt, P. P. Krüger, K. Stycz, Jeff Cooke, S. P. Littlefair, H. Odaka, Felix Jankowsky, N. Shafi, M. de Naurois, Krzysztof Katarzynski, Jim Hinton, Matteo Cerruti, P. Bordas, Robert Lahmann, F. Krayzel, V. Bertin, J. Barrios-Martí, R. Liu, Stefan Ohm, W. van Straten, Christoph Deil, J. Hossl, P. Jaroenjittichai, Léa Jouvin, R. Gracia-Ruiz, T. Andersson, W. Domainko, Gerard Fontaine, Felix Aharonian, J. F. Glicenstein, Maurizio Spurio, V. Popa, Catherine Boisson, D. Drouhin, Paolo Piattelli, Olivier Hervet, Pierre Brun, F. Voisin, M. Jongen, D. Kolitzus, C. Trichard, M. Arrieta, Utane Sawangwit, Heike Prokoph, P. T. O'Brien, Paolo Sapienza, A. Förster, Ruben Lopez-Coto, M. Lemoine-Goumard, Abdelilah Moussa, S. Eschbach, M. V. Fernandes, A.J. Heijboer, Steffen Hallmann, C. Hugon, Ruizhi Yang, D. Turpin, Werner Hofmann, Stefano Gabici, S.F. Biagi, P. Wagner, V. Marandon, Jean-Pierre Ernenwein, C. Distefano, S. Colafrancesco, D. F. E. Samtleben, Vladimir Kulikovskiy, Marek Jamrozy, I. Andreoni, Corinne Donzaud, Vikram Ravi, Joachim Hahn, Shivani Bhandari, L. Oakes, Johannes Veh, M. Tluczykont, M. Caleb, Gilles Henri, J. Bolmont, J. Hawkes, I. Sushch, S. Basa, M. Chrétien, Sarah Burke-Spolaor, M. Gajdus, G.E. Păvălaş, C. Pellegrino, H. Costantini, Peter Eger, F. Stinzing, C. van Eldik, D. Berge, G. De Bonis, B. Giebels, A. Capone, Helene Sol, J. Busto, J. Becker Tjus, J.-P. Tavernet, Gavin Rowell, M. Bryan, R. de los Reyes, P.-O. Petrucci, N. W. Pekeur, Manuel Meyer, A. Goya, M. Burgay, Miguel Ardid, D. Gottschall, Anne Lemiere, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Petroff, E, Burke-Spolaor, S, Keane, Ef, Mclaughlin, Ma, Miller, R, Andreoni, I, Bailes, M, Barr, Ed, Bernard, Sr, Bhandari, S, Bhat, Ndr, Burgay, M, Caleb, M, Champion, D, Chandra, P, Cooke, J, Dhillon, V, Farnes, J, Hardy, Lk, Jaroenjittichai, P, Johnston, S, Kasliwal, M, Kramer, M, Littlefair, Sp, Macquart, Jp, Mickaliger, M, Possenti, A, Pritchard, T, Ravi, V, Rest, A, Rowlinson, A, Sawangwit, U, Stappers, B, Sullivan, M, Tiburzi, C, van Straten, W, Albert, A, Andre, M, Anghinolfi, M, Anton, G, Ardid, M, Aubert, Jj, Avgitas, T, Baret, B, Barrios-Marti, J, Basa, S, Bertin, V, Biagi, S, Borrnuth, R, Bourret, S, Bouwhuis, Mc, Bruijn, R, Brunner, J, Busto, J, Capone, A, Caramete, L, Carr, J, Celli, S, Chiarusi, T, Circella, M, Coelho, Jab, Coleiro, A, Coniglione, R, Costantini, H, Coyle, P, Creusot, A, Deschamps, A, De Bonis, G, Distefano, C, Di Palma, I, Donzaud, C, Dornic, D, Drouhin, D, Eberl, T, El Bojaddaini, I, Elsasser, D, Enzenhofer, A, Felis, I, Fusco, La, Galata, S, Gay, P, Geisselsoder, S, Geyer, K, Giordano, V, Gleixner, A, Glotin, H, Gregoire, T, Gracia-Ruiz, R, Graf, K, Hallmann, S, van Haren, H, Heijboer, Aj, Hello, Y, Hernandez-Rey, Jj, Hossl, J, Hofestadt, J, Hugon, C, Illuminati, G, James, Cwcw, de Jong, M, Jongen, M, Kadler, M, Kalekin, O, Katz, U, Kiessling, D, Kouchner, A, Kreter, M, Kreykenbohm, I, Kulikovskiy, V, Lachaud, C, Lahmann, R, Lefevre, D, Leonora, E, Lotze, M, Loucatos, S, Marcelin, M, Margiotta, A, Marinelli, A, Martinez-Mora, Ja, Mathieu, A, Mele, R, Melis, K, Michael, T, Migliozzi, P, Moussa, A, Mueller, C, Nezri, E, Pavalas, Ge, Pellegrino, C, Perrina, C, Piattelli, P, Popa, V, Pradier, T, Quinn, L, Racca, C, Riccobene, G, Roensch, K, Sanchez-Losa, A, Saldana, M, Salvadori, I, Samtleben, Dfe, Sanguineti, M, Sapienza, P, Schnabel, J, Seitz, T, Sieger, C, Spurio, M, Stolarczyk, T, Taiuti, M, Tayalati, Y, Trovato, A, Tselengidou, M, Turpin, D, Tonnis, C, Vallage, B, Vallee, C, Van Elewyck, V, Vivolo, D, Vizzoca, A, Wagner, S, Wilms, J, Zornoza, Jd, Zuniga, J, Abdalla, H, Abramowski, A, Aharonian, F, Benkhali, Fa, Akhperjanian, Ag, Andersson, T, Anguner, Eo, Arrieta, M, Aubert, P, Backes, M, Balzer, A, Barnard, M, Becherini, Y, Tjus, Jb, Berge, D, Bernhard, S, Bernlohr, K, Blackwell, R, Bottcher, M, Boisson, C, Bolmont, J, Bordas, P, Bregeon, J, Brun, F, Brun, P, Bryan, M, Bulik, T, Capasso, M, Casanova, S, Cerruti, M, Chakraborty, N, Chalme-Calvet, R, Chaves, Rcg, Chen, A, Chevalier, J, Chretien, M, Colafrancesco, S, Cologna, G, Condon, B, Conrad, J, Cui, Y, Davids, Id, Decock, J, Degrange, B, Deil, C, Devin, J, de Wilt, P, Dirson, L, Djannati-Atai, A, Domainko, W, Donath, A, Drury, Lo, Dubus, G, Dutson, K, Dyks, J, Edwards, T, Egberts, K, Eger, P, Ernenwein, Jp, Eschbach, S, Farnier, C, Fegan, S, Fernandes, Mv, Fiasson, A, Fontaine, G, Forster, A, Funk, S, Fussling, M, Gabici, S, Gajdus, M, Gallant, Ya, Garrigoux, T, Giavitto, G, Giebels, B, Glicenstein, Jf, Gottschall, D, Goya, A, Grondin, Mh, Hadasch, D, Hahn, J, Haupt, M, Hawkes, J, Heinzelmann, G, Henri, G, Hermann, G, Hervet, O, Hinton, Ja, Hofmann, W, Hoischen, C, Holler, M, Horns, D, Ivascenko, A, Jacholkowska, A, Jamrozy, M, Janiak, M, Jankowsky, D, Jankowsky, F, Jingo, M, Jogler, T, Jouvin, L, Jung-Richardt, I, Kastendieck, Ma, Katarzynski, K, Kerszberg, D, Khelifi, B, Kieffer, M, King, J, Klepser, S, Klochkov, D, Kluzniak, W, Kolitzus, D, Komin, N, Kosack, K, Krakau, S, Kraus, M, Krayzel, F, Kruger, Pp, Laffon, H, Lamanna, G, Lau, J, Lees, Jp, Lefaucheur, J, Lefranc, V, Lemiere, A, Lemoine-Goumard, M, Lenain, Jp, Leser, E, Lohse, T, Lorentz, M, Liu, R, Lopez-Coto, R, Lypova, I, Marandon, V, Marcowith, A, Mariaud, C, Marx, R, Maurin, G, Maxted, N, Mayer, M, Meintjes, Pj, Meyer, M, Mitchell, Amw, Moderski, R, Mohamed, M, Mohrmann, L, Mora, K, Moulin, E, Murach, T, de Naurois, M, Niederwanger, F, Niemiec, J, Oakes, L, O'Brien, P, Odaka, H, Ottl, S, Ohm, S, Ostrowski, M, Oya, I, Padovani, M, Panter, M, Parsons, Rd, Pekeur, Nw, Pelletier, G, Perennes, C, Petrucci, Po, Peyaud, B, Piel, Q, Pita, S, Poon, H, Prokhorov, D, Prokoph, H, Puhlhofer, G, Punch, M, Quirrenbach, A, Raab, S, Reimer, A, Reimer, O, Renaud, M, de los Reyes, R, Rieger, F, Romoli, C, Rosier-Lees, S, Rowell, G, Rudak, B, Rulten, Cb, Sahakian, V, Salek, D, Sanchez, Da, Santangelo, A, Sasaki, M, Schlickeiser, R, Schulz, A, Schussler, F, Schwanke, U, Schwemmer, S, Settimo, M, Seyffert, A, Shafi, N, Shilon, I, Simoni, R, Sol, H, Spanier, F, Spengler, G, Spies, F, Stawarz, L, Steenkamp, R, Stegmann, C, Stinzing, F, Stycz, K, Sushch, I, Tavernet, Jp, Tavernier, T, Taylor, Am, Terrier, R, Tibaldo, L, Tiziani, D, Tluczykont, M, Trichard, C, Tuffs, R, Uchiyama, Y, van der Walt, Dj, van Eldik, C, van Rensburg, C, van Soelen, B, Vasileiadis, G, Veh, J, Venter, C, Viana, A, Vincent, P, Vink, J, Voisin, F, Volk, Hj, Vuillaume, T, Wadiasingh, Z, Wagner, Sj, Wagner, P, Wagner, Rm, White, R, Wierzcholska, A, Willmann, P, Wornlein, A, Wouters, D, Yang, R, Zabalza, V, Zaborov, D, Zacharias, M, Zanin, R, Zdziarski, Aa, Zech, A, Zefi, F, Ziegler, A, Zywucka, N, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Petroff, E., Burke-Spolaor, S., Keane, E. F., Mclaughlin, M. A., Miller, R., Andreoni, I., Bailes, M., Barr, E. D., Bernard, S. R., Bhandari, S., Bhat, N. D. R., Burgay, M., Caleb, M., Champion, D., Chandra, P., Cooke, J., Dhillon, V. S., Farnes, J. S., Hardy, L. K., Jaroenjittichai, P., Johnston, S., Kasliwal, M., Kramer, M., Littlefair, S. P., Macquart, J. P., Mickaliger, M., Possenti, A., Pritchard, T., Ravi, V., Rest, A., Rowlinson, A., Sawangwit, U., Stappers, B., Sullivan, M., Tiburzi, C., van Straten, W., Albert, A., André, M., Anghinolfi, M., Anton, G., Ardid, M., Aubert, J.-J., Avgitas, T., Baret, B., Barrios-Martí, J., Basa, S., Bertin, V., Biagi, S., Bormuth, R., Bourret, S., Bouwhuis, M.C., Bruijn, R., Brunner, J., Busto, J., Capone, A., Caramete, L., Carr, J., Celli, S., Chiarusi, T., Circella, M., Coelho, J.A.B., Coleiro, A., Coniglione, R., Costantini, H., Coyle, P., Creusot, A., Deschamps, A., De Bonis, G., Distefano, C., Palma, I. Di, Donzaud, C., Dornic, D., Drouhin, D., Eberl, T., El Bojaddaini, I., Elsässer, D., Enzenhöfer, A., Felis, I., Fusco, L.A., Galatà, S., Gay, P., Geißelsöder, S., Geyer, K., Giordano, V., Gleixner, A., Glotin, H., Grégoire, T., Gracia-Ruiz, R., Graf, K., Hallmann, S., van Haren, H., Heijboer, A.J., Hello, Y., Hernández-Rey, J.J., Hößl, J., Hofestädt, J., Hugon, C., Illuminati, G., James, C.W, de Jong, M., Jongen, M., Kadler, M., Kalekin, O., Katz, U., Kießling, D., Kouchner, A., Kreter, M., Kreykenbohm, I., Kulikovskiy, V., Lachaud, C., Lahmann, R., Lefèvre, D., Leonora, E., Lotze, M., Loucatos, S., Marcelin, M., Margiotta, A., Marinelli, A., Martínez-Mora, J.A., Mathieu, A., Mele, R., Melis, K., Michael, T., Migliozzi, P., Moussa, A., Mueller, C., Nezri, E., Păvălaş, G.E., Pellegrino, C., Perrina, C., Piattelli, P., Popa, V., Pradier, T., Quinn, L., Racca, C., Riccobene, G., Roensch, K., Sánchez-Losa, A., Saldaña, M., Salvadori, I., Samtleben, D. F. E., Sanguineti, M., Sapienza, P., Schnabel, J., Seitz, T., Sieger, C., Spurio, M., Stolarczyk, Th., Taiuti, M., Tayalati, Y., Trovato, A., Tselengidou, M., Turpin, D., Tönnis, C., Vallage, B., Vallée, C., Van Elewyck, V., Vivolo, D., Vizzoca, A., Wagner, S., Wilms, J., Zornoza, J.D., Zúñiga, J., Abdalla, H., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Akhperjanian, A.G., Andersson, T., Angüner, E.O., Arrieta, M., Aubert, P., Backes, M., Balzer, A., Barnard, M., Becherini, Y., Becker Tjus, J., Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Bulik, T., Capasso, M., Casanova, S., Cerruti, M., Chakraborty, N., Chalme-Calvet, R., Chaves, R.C.G., Chen, A., Chevalier, J., Chrétien, M., Colafrancesco, S., Cologna, G., Condon, B., Conrad, J., Cui, Y., Davids, I.D., Decock, J., Degrange, B., Deil, C., Devin, J., Dewilt, P., Dirson, L., Djannati-Ataï, A., Domainko, W., Donath, A., Drury, L.O’C., Dubus, G., Dutson, K., Dyks, J., Edwards, T., Egberts, K., Eger, P., Ernenwein, J.-P., Eschbach, S., Farnier, C., Fegan, S., Fernandes, M.V., Fiasson, A., Fontaine, G., Förster, A., Funk, S., Füßling, M., Gabici, S., Gajdus, M., Gallant, Y.A., Garrigoux, T., Giavitto, G., Giebels, B., Glicenstein, J.F., Gottschall, D., Goyal, A., Grondin, M.-H., Hadasch, D., Hahn, J., Haupt, M., Hawkes, J., Heinzelmann, G., Henri, G., Hermann, G., Hervet, O., Hinton, J.A., Hofmann, W., Hoischen, C., Holler, M., Horns, D., Ivascenko, A., Jacholkowska, A., Jamrozy, M., Janiak, M., Jankowsky, D., Jankowsky, F., Jingo, M., Jogler, T., Jouvin, L., Jung-Richardt, I., Kastendieck, M.A., Katarzyński, K., Kerszberg, D., Khélifi, B., Kieffer, M., King, J., Klepser, S., Klochkov, D., Kluźniak, W., Kolitzus, D., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krayzel, F., Krüger, P.P., Laffon, H., Lamanna, G., Lau, J., Lees, J.-P., Lefaucheur, J., Lefranc, V., Lemière, A., Lemoine-Goumard, M., Lenain, J.-P., Leser, E., Lohse, T., Lorentz, M., Liu, R., López-Coto, R., Lypova, I., Marandon, V., Marcowith, A., Mariaud, C., Marx, R., Maurin, G., Maxted, N., Mayer, M., Meintjes, P.J., Meyer, M., Mitchell, A.M.W., Moderski, R., Mohamed, M., Mohrmann, L., Morå, K., Moulin, E., Murach, T., de Naurois, M., Niederwanger, F., Niemiec, J., Oakes, L., O’Brien, P., Odaka, H., Öttl, S., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R.D., Pekeur, N.W., Pelletier, G., Perennes, C., Petrucci, P.-O., Peyaud, B., Piel, Q., Pita, S., Poon, H., Prokhorov, D., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de lo, Rieger, F., Romoli, C., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C.B., Sahakian, V., Salek, D., Sanchez, D.A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schulz, A., Schüssler, F., Schwanke, U., Schwemmer, S., Settimo, M., Seyffert, A.S., Shafi, N., Shilon, I., Simoni, R., Sol, H., Spanier, F., Spengler, G., Spies, F., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Stycz, K., Sushch, I., Tavernet, J.-P., Tavernier, T., Taylor, A.M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tuffs, R., Uchiyama, Y., Walt, D.J. van der, van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H.J., Vuillaume, T., Wadiasingh, Z., Wagner, S.J., Wagner, P., Wagner, R.M., White, R., Wierzcholska, A., Willmann, P., Wörnlein, A., Wouters, D., Yang, R., Zabalza, V., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A.A., Zech, A., Zefi, F., Ziegler, A., Żywucka, N., High Energy Astrophys. & Astropart. Phys (API, FNWI), KM3NeT (IHEF, IoP, FNWI), Faculty of Science, Gravitation and Astroparticle Physics Amsterdam, ATLAS (IHEF, IoP, FNWI), GRAPPA (ITFA, IoP, FNWI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Andre, M., Aubert, J. -J., Barrios-Marti, J., Bouwhuis, M. C., Coelho, J. A. B., Di Palma, I., Elsasser, D., Enzenhofer, A., Fusco, L. A., Galata, S., Geisselsoder, S., Gregoire, T., Heijboer, A. J., Hernandez-Rey, J. J., Hobl, J., Hofestadt, J., James, C. W., Kiebling, D., Lefevre, D., Martinez-Mora, J. A., Pavalas, G. E., Sanchez-Losa, A., Saldana, M., Stolarczyk, T., Tonnis, C., Vallee, C., Zornoza, J. D., Zuniga, J., Ait Benkhali, F., Akhperjanian, A. G., Anguner, E. O., Bernlohr, K., Bottcher, M., Chaves, R. C. G., Chretien, M., Davids, I. D., Djannati-Atai, A., Drury, L. O'C., Ernenwein, J. -P., Fernandes, M. V., Forster, A., Fubling, M., Gallant, Y. A., Glicenstein, J. F., Grondin, M. -H., Hinton, J. A., Kastendieck, M. A., Katarzynski, K., Khelifi, B., Kluzniak, W., Komin, N., Kruger, P. P., Lees, J. -P., Lemiere, A., Lenain, J. -P., Lopez-Coto, R., Meintjes, P. J., Mitchell, A. M. W., Mora, K., O'Brien, P., Ottl, S., Parsons, R. D., Pekeur, N. W., Petrucci, P. -O., Puhlhofer, G., de los Reyes, R., Rulten, C. B., Sanchez, D. A., Schussler, F., Seyffert, A. S., Stawarz, L., Tavernet, J. -P., Taylor, A. M., van der Walt, D. J., Volk, H. J., Wagner, S. J., Wagner, R. M., Wornlein, A., Zdziarski, A. A., Zywucka, N., Centre Tecnològic de Vilanova i la Geltrú, and Universitat Politècnica de Catalunya. LAB - Laboratori d'Aplicacions Bioacústiques
Subjects: Astrofísica, Astronomy, Astrophysics, Surveys, ISM: structure, Methods: data analysis, Polarization, Astronomy and Astrophysics, Space and Planetary Science, 01 natural sciences, Radio telescopes, data analysis [Methods], 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Line-of-sight, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Linear polarization, Fast radio burst, Galactic Center, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics - High Energy Astrophysical Phenomena, polarization–methods, dataanalysis–surveys–ISM, structure, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Radio telescope, 0103 physical sciences, Neutrins, Neutrinos, Astrophysics::Galaxy Astrophysics, Astroparticle physics, Telescopis, 010308 nuclear & particles physics, Galactic plane, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], FISICA APLICADA, ddc:520, polarization – methods: data analysis – surveys – ISM: structure, structure [ISM], Methods: data analysi
Abstract: Monthly notices of the Royal Astronomical Society 469(4), 4465 – 4482 (2017). doi:10.1093/mnras/stx1098, We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 ± 0.8 pc cm$^{−3}$, a pulse duration of 2.8 $^{+1.2}_{-0.5}$ ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7$^{+0.2}_{-0.1}$ Jy. The FRB originated at a Galactic longitude and latitude of 24.66°, 5.28° and 25° away from the Galactic Center. The burst was found to be 43 ± 5 per cent linearly polarized with a rotation measure (RM) in the range −9, Published by Oxford Univ. Press, Oxford
Published: 2017

48. LOFAR MSSS: The Scaling Relation between AGN Cavity Power and Radio Luminosity at Low Radio Frequencies

Author: D. D. Mulcahy, Michael W. Wise, Aleksandar Shulevski, Marco Iacobelli, M. Pandey-Pommier, Antonia Rowlinson, George Heald, G. Gürkan, Adam Stewart, Jeremy J. Harwood, Emanuela Orru, Błażej Nikiel-Wroczyński, C. J. Riseley, Anna M. M. Scaife, John McKean, Leith Godfrey, R. Pizzo, M. de Vries, Huib Intema, Cyril Tasse, J. W. Broderick, G. Kokotanekov, Chiara Ferrari, D. A. Rafferty, D. Carbone, V. N. Pandey, Judith H. Croston, Huub Röttgering, Luke Pratley, A. O. Clarke, Laura Birzan, Annalisa Bonafede, A. J. van der Horst, Rene P. Breton, R. J. van Weeren, W. Jurusik, Martin J. Hardcastle, S. S. Sridhar, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Centre de Recherche Astrophysique de Lyon ( CRAL ), École normale supérieure - Lyon ( ENS Lyon ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Galaxies, Etoiles, Physique, Instrumentation ( GEPI ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Joseph Louis LAGRANGE ( LAGRANGE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Observatoire de la Côte d'Azur, Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), High Energy Astrophys. & Astropart. Phys (API, FNWI), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: clusters: individual: MS 0735.6+7421 [galaxies], Astronomy, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics, galaxies: clusters: individual: Perseus, 01 natural sciences, galaxies: clusters: individual: 2A 0335+096, law.invention, law, HYDRA-A, 010303 astronomy & astrophysics, media_common, Physics, MAGNETIC-FIELD, galaxies: clusters: individual: MS 0735.6+7421, clusters: individual: A2199 [galaxies], clusters: intracluster medium [galaxies], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Radio frequency, INTRACLUSTER MEDIUM, galaxies: clusters: individual: A2199, Astrophysics - Cosmology and Nongalactic Astrophysics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), PERSEUS CLUSTER, galaxies: clusters: intracluster medium, GASEOUS ATMOSPHERE, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, clusters: individual: 2A 0335+096 [galaxies], clusters: individual: Perseus [galaxies], Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, RAY-EMITTING GAS, 0103 physical sciences, Cluster (physics), Scaling, Astrophysics::Galaxy Astrophysics, VLA OBSERVATIONS, 010308 nuclear & particles physics, Bolometer, JET-POWER, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), X-rays: galaxies: clusters, galaxies: clusters [X-rays], GALAXY CLUSTERS, SKY SURVEY, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: International audience; We present a new analysis of the widely used relation between cavity power and radio luminosity in clusters of galaxies with evidence for strong AGN feedback. We studied the correlation at low radio frequencies using two new surveys – the first alternative data release of the TIFR GMRT Sky Survey (TGSS ADR1) at 148 MHz and LOFAR’s firstall-sky survey, the Multifrequency Snapshot Sky Survey (MSSS) at 140 MHz. We find a scaling relation Pcav ∝ Lβ148, with a logarithmic slope of β = 0.51 ± 0.14, which is in good agreement with previous results based on data at 327 MHz. The large scatter present in this correlation confirms the conclusion reached at higher frequencies that the total radio luminosity at a single frequency is a poor predictor of the total jet power. Previous studies have shown that the magnitude of this scatter can be reduced when bolometric radio luminosity corrected for spectral aging is used. We show that including additional measurements at 148 MHz alone is insufficient to improve this correction and further reduce the scatter in the correlation. For a subset of four well-resolved sources, we examined the detected extended structures at low frequencies and compare with the morphology known from higher frequency images and Chandra X-ray maps. In the case of Perseus we discuss details in the structures of the radio mini-halo, while in the 2A 0335+096 cluster we observe new diffuse emission associated with multiple X-ray cavities and likely originating from past activity. For A2199 and MS 0735.6+7421, we confirm that the observed low-frequency radio lobes are confined to the extents known from higher frequencies. This new low-frequency analysis highlights the fact that existing cavity power to radio luminosity relations are based on a relatively narrow range of AGN outburst ages. We discuss how the correlation could be extended using low frequency data from the LOFAR Two-metre Sky Survey (LoTSS) in combination with future, complementary deeper X-ray observations. Key words: galaxies: clusters: individual: 2A 0335+096 / galaxies: clusters: individual: Perseus / X-rays: galaxies: clusters / galaxies: clusters: individual: A2199 / galaxies: clusters: individual: MS 0735.6+7421 / galaxies: clusters: intracluster medium
Published: 2017

49. A search for long-time-scale, low-frequency radio transients

Author: Christene Lynch, Chen Wu, Lister Staveley-Smith, J. L. B. Line, Ron Ekers, Anna D. Kapińska, Keith W. Bannister, Huib Intema, Christian Wolf, Pietro Procopio, Luke Hindson, Christopher A. Onken, Preshanth Jagannathan, K. S. Dwarakanath, Bryan Gaensler, Paul Hancock, Fang Yuan, Joseph R. Callingham, Natasha Hurley-Walker, Antonia Rowlinson, Emil Lenc, Bi-Qing For, Martin Bell, Steven Tingay, A. R. Offringa, Benjamin McKinley, Tara Murphy, Steve Croft, Qinghua Zheng, John Morgan, Melanie Johnston-Hollitt, David L. Kaplan, Randall B. Wayth, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Active galactic nucleus, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, FOS: Physical sciences, Murchison Widefield Array, Astrophysics, Astronomy & Astrophysics, Low frequency, 01 natural sciences, law.invention, Telescope, law, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, Physics, Astronomy, Astronomy and Astrophysics, LOFAR, Redshift survey, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Radio frequency
Abstract: We present a search for transient and highly variable sources at low radio frequencies (150-200 MHz) that explores long timescales of 1-3 years. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cutoff and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 +/- 26 mJy at 147.5 MHz. This gives a transient surface density of rho = (6.2 +/- 6) x 10-5 deg-2 . We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues., Comment: 12 pages, 8 figures, accepted by MNRAS
Published: 2017

50. Circular polarization in the optical afterglow of GRB 121024A

Author: Fabian Knust, A. J. van der Horst, Gianpiero Tagliaferri, Andreja Gomboc, Richard Willingale, Nial R. Tanvir, S. D. Vergani, V. Sudilovsky, R. Karjalainen, David M. Russell, C. Farina, Stefano Covino, Antonia Rowlinson, Zhi-Ping Jin, Karla Varela, Ralph A. M. J. Wijers, R. L. C. Starling, Ruben Salvaterra, Johan P. U. Fynbo, Jochen Greiner, O. E. Hartoog, Yi-Zhong Fan, J. Elliott, P. T. O'Brien, S. di Serego Alighieri, Michiel Min, Jens Hjorth, S. Klose, Carole Mundell, Kenji Toma, D. Gotz, Elena Pian, J. Gorosabel, Shiho Kobayashi, Patricia Schady, Chryssa Kouveliotou, Andrew J. Levan, K. Wiersema, Sergio Campana, P. A. Curran, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Multidisciplinary, 010308 nuclear & particles physics, Linear polarization, Scattering, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Optical polarization, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Plasma, Polarization (waves), 01 natural sciences, Afterglow, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, 010303 astronomy & astrophysics, Circular polarization
Abstract: Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet, when measured minutes after the burst, and the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after burst in GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and negligable circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blastwave. Here we report the detection of circularly polarized optical light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets., Published as Wiersema et al. 2014, Nature 509, 201-204. This is the version prior to final editing; please see official published version for the final version and higher quality images
Published: 2014

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

90 results on '"Antonia Rowlinson"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources