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1. Student Development through Participation in School Sponsored Extracurricular Activities in an Elementary School Setting

Author: Michael W. Wise
Abstract: Extracurricular programs offered in the K-5 school setting are places in which students can affirm their sense of belonging and make developmental, social, and academic progress. This study examines students' participation in one or more of thirteen extracurricular programs offered at a Southern California elementary school; the year in which the study was implemented coincides with students' first year back to full capacity, full day attendance in-person since the global COVID-19 pandemic necessitated closures and restrictions to in-person school attendance. Supplying opportunities for student enrichment, and by extension community enrichment, this study examined correlations between sense of belonging, positive attendance, prosocial behaviors, and academic growth associated with participation in school-based, extracurricular programs. Participants' social construction of reality through the input of "cultural artifacts", "social activity", and "language" was examined using social constructivist and sociocultural frameworks (Kim, 2014; Vygotsky 1934, 1978). Anticipated growth was focused upon social and academic development and tied to standardized testing metrics as evaluative markers, and teacher and parent observation and assessment. The evaluated data for this mixed methods study is inclusive of a linear regression model to determine prediction of correlation between math and English Language arts (ELA) and positive school attendance were correlated to student participation in school-based extracurricular activities. Focus groups, in which semi-structured interviews, occurred yielded the qualitative data. SPSS data outputs using information from all enrolled students in grades 1 through 5, student, parent, and teacher interviews were instructive in determining any positive yield in the case being studied. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]
Published: 2022

2. Late-time X-ray observations of the transient source Cygnus A-2

Author: Bradford Snios, Martijn De Vries, Paul E J Nulsen, Ralph P Kraft, Aneta Siemiginowska, and Michael W Wise
Published: 2022
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3. RFI flagging implications for short-duration transients.

Author: Yvette N. Cendes, Peeyush Prasad, Antonia Rowlinson, Ralph A. M. J. Wijers, John D. Swinbank, Casey J. Law, Alexander J. van der Horst, Dario Carbone, Jess W. Broderick, Tim D. Staley, Adam J. Stewart, Folkert Huizinga, Gijs J. Molenaar, Anastasia Alexov, Martin E. Bell, Thijs Coenen, Stéphane Corbel, Jochen Eislöffel, Robert P. Fender, Jean-Mathias Grießmeier, Peter G. Jonker, Michael Kramer, Masaya Kuniyoshi, Benjamin W. Stappers, Michael W. Wise, and Philippe Zarka
Published: 2018
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4. The LOFAR Transients Pipeline.

Author: John D. Swinbank, Tim D. Staley, Gijs J. Molenaar, Evert Rol, Antonia Rowlinson, Bart Scheers, Hanno Spreeuw, Martin E. Bell, Jess W. Broderick, Dario Carbone, Hugh Garsden, Alexander J. van der Horst, Casey J. Law, Michael W. Wise, Rene P. Bretonm, Yvette N. Cendes, Stéphane Corbel, Jochen Eislöffel, Heino Falcke, Robert P. Fender, Jean-Mathias Grießmeier, Jason W. T. Hessels, Benjamin W. Stappers, Adam J. Stewart, Ralph A. M. J. Wijers, Rudy Wijnands, and Philippe Zarka
Published: 2015
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5. Nuclear Receptor Signaling Atlas: Opening Access to the Biology of Nuclear Receptor Signaling Pathways.

Author: Lauren B Becnel, Yolanda F Darlington, Scott A Ochsner, Jeremy R Easton-Marks, Christopher M Watkins, Apollo McOwiti, Wasula H Kankanamge, Michael W Wise, Michael DeHart, Ronald N Margolis, and Neil J McKenna
Subjects: Medicine, Science
Abstract: Signaling pathways involving nuclear receptors (NRs), their ligands and coregulators, regulate tissue-specific transcriptomes in diverse processes, including development, metabolism, reproduction, the immune response and neuronal function, as well as in their associated pathologies. The Nuclear Receptor Signaling Atlas (NURSA) is a Consortium focused around a Hub website (www.nursa.org) that annotates and integrates diverse 'omics datasets originating from the published literature and NURSA-funded Data Source Projects (NDSPs). These datasets are then exposed to the scientific community on an Open Access basis through user-friendly data browsing and search interfaces. Here, we describe the redesign of the Hub, version 3.0, to deploy "Web 2.0" technologies and add richer, more diverse content. The Molecule Pages, which aggregate information relevant to NR signaling pathways from myriad external databases, have been enhanced to include resources for basic scientists, such as post-translational modification sites and targeting miRNAs, and for clinicians, such as clinical trials. A portal to NURSA's Open Access, PubMed-indexed journal Nuclear Receptor Signaling has been added to facilitate manuscript submissions. Datasets and information on reagents generated by NDSPs are available, as is information concerning periodic new NDSP funding solicitations. Finally, the new website integrates the Transcriptomine analysis tool, which allows for mining of millions of richly annotated public transcriptomic data points in the field, providing an environment for dataset re-use and citation, bench data validation and hypothesis generation. We anticipate that this new release of the NURSA database will have tangible, long term benefits for both basic and clinical research in this field.
Published: 2015
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6. Simulations of the merging cluster of galaxies Cygnus A

Author: J. M. F. Donnert, Timo Halbesma, M. N. de Vries, Michael W. Wise, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Active galactic nucleus, 010308 nuclear & particles physics, Cluster state, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Mass ratio, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Intracluster medium, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Cluster (physics), Cygnus A, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics
Abstract: The archetype FR-II galaxy Cygnus A lies in a moderately rich cluster about to undergo a major merger. We study the pre-merger Cygnus cluster environment using smoothed particle hydrodynamics simulations constrained by 2Ms of Chandra observations of the hot intracluster medium. The observations constrain the total gravitating mass and concentration parameter, and the simulations provide the quiescent and merger-enhanced temperature profiles of the pre- and post-merger of the cluster excluding the central active galactic nucleus (AGN). We present the first detailed model of the sub cluster north west of Cygnus A, named CygNW. We find a lower baryon fraction and higher concentration parameter for CygA than expected from known scaling relations in the literature. The model suggests the Cygnus cluster hosts a pre-merger with a progenitor mass ratio of about 1.5:1 at the virial radius. We notice that the intra cluster medium is heated as a result of the merger, but we find no evidence for a (pre-)merger shock in the interstitial region between both cluster haloes. We attribute the merger-induced heating to compression of the cluster outskirts. The smooth model obtained from our simulations is subtracted from the observed cluster state and shows residual temperature structure that is neither hydrostatic nor merger-heated cluster gas. We speculate that this residual heating may result from previous AGN activity over the last ∼100 Myr.
Published: 2019

7. The high energy Universe at ultra-high resolution: the power and promise of X-ray interferometry

Author: Katja Poppenhäger, Sera Markoff, Piergiorgio Casella, Francesca Panessa, Erin Kara, Ralph A. M. J. Wijers, Michal Bursa, Richard Willingale, Roland den Hartog, Keith C. Gendreau, Michael W. Wise, Stefano Bianchi, Agata Różańska, Thomas Dauser, Phil Uttley, Jan-Willem den Herder, Maria Diaz Trigo, Webster Cash, Elisa Costantini, Jiri Svoboda, Cosimo Bambi, Jörn Wilms, Victoria Grinberg, Didier Barret, Beatriz Mingo, Massimo Cappi, Adam Ingram, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), 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), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), API Other Research (FNWI), Low Energy Astrophysics (API, FNWI), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), 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)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Active galactic nucleus, Event horizon, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Observable universe, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, X-ray astronomy, symbols.namesake, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Instrumentation, Astrophysics::Galaxy Astrophysics, media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, 010308 nuclear & particles physics, Astronomy and Astrophysics, Quasar, Universe, Interferometry, 13. Climate action, Space and Planetary Science, symbols, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Hubble's law
Abstract: We propose the development of X-ray interferometry (XRI), to reveal the universe at high energies with ultra-high spatial resolution. With baselines which can be accommodated on a single spacecraft, XRI can reach 100 $\mu$as resolution at 10 \AA (1.2 keV) and 20 $\mu$as at 2 \AA (6 keV), enabling imaging and imaging-spectroscopy of (for example) X-ray coronae of nearby accreting supermassive black holes (SMBH) and the SMBH `shadow'; SMBH accretion flows and outflows; X-ray binary winds and orbits; stellar coronae within ~100 pc and many exoplanets which transit across them. For sufficiently luminous sources XRI will resolve sub-pc scales across the entire observable universe, revealing accreting binary SMBHs and enabling trigonometric measurements of the Hubble constant with X-ray light echoes from quasars or explosive transients. A multi-spacecraft `constellation' interferometer would resolve well below 1 $\mu$as, enabling SMBH event horizons to be resolved in many active galaxies and the detailed study of the effects of strong field gravity on the dynamics and emission from accreting gas close to the black hole., Comment: White Paper submitted in response to ESA's Voyage 2050 call
Published: 2021

8. The development of a testbed for the X-ray Interferometer mission

Author: Richard Willingale, Michael W. Wise, Roland den Hartog, Henk F.C. Hoevers, Jan-Willem den Herder, and Phil Uttley
Subjects: Wavefront, Spacecraft, Computer science, business.industry, Testbed, FOS: Physical sciences, X-ray interferometer, Interferometry, Angular resolution, Aerospace engineering, business, Baseline (configuration management), Focus (optics), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: An X-ray Interferometer (XRI) has recently been proposed as a theme for ESA's Voyage 2050 planning cycle, with the eventual goal to observe the X-ray sky with an unprecedented angular resolution better than 1 micro arcsec (5 prad) [1]. A scientifically very interesting mission is possible on the basis of a single spacecraft [2], owing to the compact 'telephoto' design proposed earlier by Willingale [3]. Between the practical demonstration of X-ray interferometry at 1 keV by Cash et al. [4] with a 1 mm baseline and 0.1 arcsec effective resolution to a mission flying an interferometer with a baseline of one or more meters, an effective collecting area of square meters and micro arcsec resolution lie many milestones. The first important steps to scale up from a laboratory experiment to a viable mission concept will have to be taken on a scalable and flexible testbed set-up. Such a testbed cannot singularly focus on the optical aspects, but should simultaneously address the thermal and mechanical stability of the interferometer. A particular challenge is the coherent X-ray source, which should provide a wavefront at the entrance of the interferometer that is transversely coherent over a distance at least equal to the baseline, and bright enough. In this paper, we will explore the build-up of a testbed in several stages, with increasing requirements on optical quality and associated thermo-mechanical control and source sophistication, with the intent to guide the technological development of X-ray interferometry from the lab to space in a sequence of achievable milestones., Comment: 12 pages, 4 figures, final draft manuscript for the SPIE Astronomical Telescopes + Instrumentation online conference, 2020
Published: 2021
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9. The X-Ray Cavity Around Hotspot E in Cygnus A: Tunneled by a Deflected Jet

Author: Amalya C. Johnson, Martijn de Vries, Lerato Sebokolodi, Bradford Snios, Paul Nulsen, Michael W. Wise, Ralph P. Kraft, and Richard A. Perley
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010504 meteorology & atmospheric sciences, Radio galaxy, X-ray, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Lobe, medicine.anatomical_structure, Space and Planetary Science, Intracluster medium, 0103 physical sciences, Hotspot (geology), medicine, Outflow, Surface brightness, Cygnus A, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: The powerful FR II radio galaxy Cygnus A exhibits primary and secondary hotspots in each lobe. A 2 Msec Chandra X-ray image of Cygnus A has revealed an approximately circular hole, with a radius of 3.9 kpc, centered on the primary hotspot in the eastern radio lobe, hotspot E. We infer the distribution of X-ray emission on our line-of-sight from an X-ray surface brightness profile of the radio lobe adjacent to the hole and use it to argue that the hole is excavated from the radio lobe. The surface brightness profile of the hole implies a depth at least 1.7 $\pm$ 0.3 times greater than its projected width, requiring a minimum depth of 13.3 $\pm$ 2.3 kpc. A similar hole observed in the 5 GHz VLA radio map reinforces the argument for a cavity lying within the lobe. We argue that the jet encounters the shock compressed intracluster medium at hotspot E, passing through one or more shocks as it is deflected back into the radio lobe. The orientation of Cygnus A allows the outflow from hotspot E to travel almost directly away from us, creating an elongated cavity, as observed. These results favor models for multiple hotspots in which an FR II jet is deflected at a primary hotspot, then travels onward to deposit the bulk of its power at a secondary hotspot, rather than the dentist drill model., Accepted to ApJ, 12 pages, 7 figures, 5 tables
Published: 2020

10. The X-ray ribs within the cocoon shock of Cygnus A

Author: Alastair C. Edge, Bradford Snios, Michael W. Wise, William G. Mathews, Robert Laing, Martin J. Hardcastle, Paul Nulsen, Ryan T. Duffy, M. N. de Vries, Leith Godfrey, Chris Carilli, D. Rafferty, Mark Birkinshaw, Judith H. Croston, Richard A. Perley, Brian R. McNamara, John McKean, Diana M Worrall, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Sterrenkunde
Subjects: active [Galaxies], Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, galaxies: individual: Cygnus A, 0103 physical sciences, Cluster (physics), Cygnus A, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, radio continuum: galaxies, Jet (fluid), Shock (fluid dynamics), 010308 nuclear & particles physics, Astronomy and Astrophysics, Debris, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies [X-rays], Core (optical fiber), Temperature gradient, X-rays: galaxies, galaxies: active, galaxies: individual: Cygnus A, radio continuum: galaxies, X-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), individual: Cygnus A- radio continuum: galaxies [Galaxies], Astrophysics - High Energy Astrophysical Phenomena
Abstract: We use new and archival Chandra observations of Cygnus A, totalling $\sim$1.9 Ms, to investigate the distribution and temperature structure of gas lying within the projected extent of the cocoon shock and exhibiting a rib-like structure. We confirm that the X-rays are dominated by thermal emission with an average temperature of around 4 keV, and have discovered an asymmetry in the temperature gradient, with the southwestern part of the gas cooler than the rest by up to 2 keV. Pressure estimates suggest that the gas is a coherent structure of single origin located inside the cocoon, with a mass of roughly $2\times10^{10} M_{\odot}$. We conclude that the gas is debris resulting from disintegration of the cool core of the Cygnus A cluster after the passage of the jet during the early stages of the current epoch of activity. The 4 keV gas now lies on the central inside surface of the hotter cocoon rim. The temperature gradient could result from an offset between the centre of the cluster core and the Cygnus A host galaxy at the switch-on of current radio activity., 15 pages, 12 figures, accepted by MNRAS
Published: 2018

11. 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

12. A large light-mass component of cosmic rays at 10(17)-10(17.5) electronvolts from radio observations

Author: Vishambhar Pandey, D. D. Mulcahy, M. A. Garrett, J. van Leeuwen, Tim Hassall, Adam Deller, Harvey Butcher, D. Engels, H. Paas, John Conway, J. E. Enriquez, A. I. F. Stewart, M. Pandey-Pommier, Matthias Steinmetz, Rob Fender, B. Ciardi, M. Pietka, E. Juette, G. van Diepen, P. N. Best, M. C. Toribio, A. Horneffer, Chiara Ferrari, M. P. van Haarlem, S. Duscha, Mark J. Bentum, Stefan J. Wijnholds, Jochen Eislöffel, Sarod Yatawatta, Emanuela Orrú, M. Kuniyoshi, Michael Kramer, Anna Nelles, C. Vogt, R. J. van Weeren, Martin Bell, Maaijke Mevius, John D. Swinbank, P. Maat, Matthias Hoeft, M. J. Norden, Pim Schellart, D. McKay-Bukowski, J. A. Zensus, John McKean, Dominik J. Schwarz, Richard Fallows, Aris Karastergiou, Ph. Zarka, V. I. Kondratiev, T. N. G. Trinh, Stijn Buitink, Heino Falcke, Michael W. Wise, Jörg P. Rachen, Benjamin Stappers, Jason W. T. Hessels, J. Sluman, Gianni Bernardi, Jörg R. Hörandel, I. M. Avruch, James M. Anderson, F. de Gasperin, Frank Breitling, Roberto Pizzo, H. J. A. Röttgering, Satyendra Thoudam, G. Kuper, Olaf Wucknitz, M. Serylak, H. Munk, Wilfred Frieswijk, Ashish Asgekar, Marcus Brüggen, M. Iacobelli, Y. Tang, W. Reich, S. ter Veen, A. W. Gunst, Anna M. M. Scaife, Laura Rossetto, Ralph A. M. J. Wijers, A. G. Polatidis, Rebecca McFadden, Arthur Corstanje, Annalisa Bonafede, Christian Vocks, G. M. Loose, Sera Markoff, Jean-Mathias Grießmeier, Michel Tagger, D. Carbone, R. C. Vermeulen, T. Huege, Olaf Scholten, Oleg Smirnov, Huib Intema, Cyril Tasse, J. W. Broderick, E. de Geus, R. J. Dettmar, George Heald, W. N. Brouw, Gottfried Mann, High Energy Astrophys. & Astropart. Phys (API, FNWI), Radboud University [Nijmegen], Netherlands Institute for Radio Astronomy (ASTRON), Karlsruhe Institute of Technology (KIT), University of Groningen [Groningen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Laboratoire Analyse, Géométrie et Applications (LAGA), Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris 13 (UP13)-Institut Galilée-Centre National de la Recherche Scientifique (CNRS), Institute for Mathematics Applied to Geoscience, National Center for Atmospheric Research [Boulder] (NCAR), SRON Netherlands Institute for Space Research (SRON), Australia Telescope National Facility (ATNF), Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of Edinburgh, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), University of Southampton, Kapteyn Astronomical Institute [Groningen], University of Amsterdam [Amsterdam] (UvA), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Onsala Space Observatory, Dept. of Radio and Space Science, Chalmers University of Technology, Chalmers University of Technology [Göteborg], Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Medstar Research Institute, Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], Thüringer Landessternwarte Tautenburg (TLS), SETI Institute, Institute of Mathematical and Physical Sciences, Département de Géologie, Université de Montréal (UdeM), Leiden Observatory [Leiden], Universiteit 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)-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), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Max-Planck-Institut für Radioastronomie (MPIFR), Oxford Astrophysics, University of Oxford, Columbia Astrophysics Laboratory (CAL), Columbia University [New York], 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), 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), Rhodes University, Grahamstown, 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), SKA South Africa, Ska South Africa, Galaxies, Etoiles, Physique, Instrumentation (GEPI), 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), Finca El Encin, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Observatoire de Paris - Site de Paris (OP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (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, European Project: 227610,EC:FP7:ERC,ERC-2008-AdG,LOFAR-AUGER(2009), European Project: 640130,H2020,ERC-2014-STG,LOFAR(2015), Radboud university [Nijmegen], Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology, nstitute for Nuclear Physics (IKP), Karlsruhe Institute of Technology, Université Paris 8 Vincennes-Saint-Denis (UP8)-Centre National de la Recherche Scientifique (CNRS)-Institut Galilée-Université Paris 13 (UP13), Universiteit Leiden [Leiden], 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), University of Oxford [Oxford], 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), Research unit Astroparticle Physics, Astronomy, and Kapteyn Astronomical Institute
Subjects: TELESCOPE, High-energy astronomy, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Cosmic ray, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, EXTENSIVE AIR-SHOWERS, 01 natural sciences, 0103 physical sciences, 010303 astronomy & astrophysics, Astroparticle physics, Physics, Multidisciplinary, COSMIC cancer database, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, LOFAR, ENERGY-SPECTRUM, SIMULATIONS, PULSES, High-energy astrophysics, Air shower, 13. Climate action, [SDU]Sciences of the Universe [physics], ARRAY, Neutrino, Particle astrophysics, EMISSION
Abstract: Cosmic rays are the highest-energy particles found in nature. Measurements of the mass composition of cosmic rays with energies of 1017–1018 electronvolts are essential to understanding whether they have galactic or extragalactic sources. It has also been proposed that the astrophysical neutrino signal1 comes from accelerators capable of producing cosmic rays of these energies2. Cosmic rays initiate air showers—cascades of secondary particles in the atmosphere—and their masses can be inferred from measurements of the atmospheric depth of the shower maximum3 (Xmax; the depth of the air shower when it contains the most particles) or of the composition of shower particles reaching the ground4. Current measurements5 have either high uncertainty, or a low duty cycle and a high energy threshold. Radio detection of cosmic rays6,7,8 is a rapidly developing technique9 for determining Xmax (refs 10, 11) with a duty cycle of, in principle, nearly 100 per cent. The radiation is generated by the separation of relativistic electrons and positrons in the geomagnetic field and a negative charge excess in the shower front6,12. Here we report radio measurements of Xmax with a mean uncertainty of 16 grams per square centimetre for air showers initiated by cosmic rays with energies of 1017–1017.5 electronvolts. This high resolution in Xmax enables us to determine the mass spectrum of the cosmic rays: we find a mixed composition, with a light-mass fraction (protons and helium nuclei) of about 80 per cent. Unless, contrary to current expectations, the extragalactic component of cosmic rays contributes substantially to the total flux below 1017.5 electronvolts, our measurements indicate the existence of an additional galactic component, to account for the light composition that we measured in the 1017–1017.5 electronvolt range.
Published: 2019

13. 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

14. A radio ridge connecting two galaxy clusters in a filament of the cosmic web

Author: L. Feretti, Timothy W. Shimwell, R. Pizzo, H. J. A. Röttgering, Michael W. Wise, Gianni Bernardi, Matteo Murgia, Serena Manti, Claudio Gheller, Anna M. M. Scaife, H. Junklewitz, Gianfranco Brunetti, Franco Vazza, Marco Iacobelli, V. Vacca, Rossella Cassano, Matthias Hoeft, Rosita Paladino, Federica Govoni, Annalisa Bonafede, Marcus Brüggen, Emanuela Orru, Gabriele Giovannini, Chiara Ferrari, F. Loi, F. de Gasperin, Cathy Horellou, R. J. van Weeren, Torsten A. Enßlin, Govoni F., Orru E., Bonafede A., Iacobelli M., Paladino R., Vazza F., Murgia M., Vacca V., Giovannini G., Feretti L., Loi F., Bernardi G., Ferrari C., Pizzo R.F., Gheller C., Manti S., Bruggen M., Brunetti G., Cassano R., De Gasperin F., Ensslin T.A., Hoeft M., Horellou C., Junklewitz H., Rottgering H.J.A., Scaife A.M.M., Shimwell T.W., Van Weeren R.J., and Wise M.
Subjects: nearby, shock acceleration, binary cluster, Astrophysics::High Energy Astrophysical Phenomena, Population, relics, FOS: Physical sciences, Electron, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Relativistic particle, Protein filament, 0103 physical sciences, emission, 010306 general physics, education, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Physics, education.field_of_study, geography, magnetic fields, radio observations, Multidisciplinary, geography.geographical_feature_category, cd clusters, LOFAR, dynamics, Astrophysics - Astrophysics of Galaxies, Magnetic field, Ridge, Astrophysics of Galaxies (astro-ph.GA)
Abstract: Galaxy clusters are the most massive gravitationally bound structures in the Universe. They grow by accreting smaller structures in a merging process that produces shocks and turbulence in the intra-cluster gas. We observed a ridge of radio emission connecting the merging galaxy clusters Abell 0399 and Abell 0401 with the Low Frequency Array (LOFAR) at 140 MHz. This emission requires a population of relativistic electrons and a magnetic field located in a filament between the two galaxy clusters. We performed simulations to show that a volume-filling distribution of weak shocks may re-accelerate a pre-existing population of relativistic particles, producing emission at radio wavelengths that illuminates the magnetic ridge., Comment: Published in Science
Published: 2019

15. Signatures of multiple episodes of AGN activity in the core of Abell 1795

Author: Hubertus Intema, Michael W. Wise, M. de Vries, G. Kokotanekov, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Giant Metrewave Radio Telescope, Spectral index, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Methods observational, Astrophysics - Astrophysics of Galaxies, Core (optical fiber), Space and Planetary Science, Observatory, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Surface brightness, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: In this paper we analyze AGN activity signatures in the rich nearby galaxy cluster Abell 1795 aiming to confirm and characterize the long-term feedback history in the system. We combine radio observations at 610 and 235 MHz from the Giant Metrewave Radio Telescope (GMRT) with 3.4 Msec X-ray data from the Chandra Observatory. Extracting radial temperature profiles, as well as X-ray and radio surface brightness profiles in three directions showing major morphological disturbances, we highlight the signatures of activity in the system. For the first time we observe radio emission corresponding to the NW X-ray depression, which provides evidence in favor of the classification of the depression as a cavity. We identify two other X-ray cavities situated NW and SW of the AGN. While the central radio emission corresponding to the inner cavities shows a flatter spectral index, the radio extensions associated with the farthest X-ray cavities consist of aged plasma. All observed signatures both in radio and X-ray are consistent with several consecutive episodes of AGN activity, which gave rise to the observed morphology NW and SW from the core. In the southern region, we confirm the cooling wake hypothesis for the origin of the long tail. The deep X-ray data also allows us to distinguish significant distortions in the tail’s inner parts, which we attribute to the activity of the AGN.
Published: 2018

16. Division B Commission 5

Author: Michael W. Wise, Elizabeth Griffin, Heinz Andernach, Marsha Bishop, Daniel Egret, Robert J. Hanisch, Masatoshi Ohishi, Douglas Tody, Fabio Pasian, Tara Murphy, Ajit Kembhavi, Anja Schroeder, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Restructuring, business.industry, Task force, Computer science, Data management, Library science, Astronomy and Astrophysics, Commission, Data preservation, Documentation, Space and Planetary Science, Telecommunications, business, Working group
Abstract: IAU Commission 5, Documentation and Astronomical Data, continued its mission of promoting and supporting sound practices of data management, data dissemination, and data preservation over the past three years. The Commission also prepared its proposal for continuation, with some changes in emphasis, after the IAU's commission restructuring program. Below we report on the activities of the various Working Groups and the one Task Force in Commission 5.
Published: 2016

17. 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

18. LOFAR 150-MHz observations of the Boötes field: catalogue and source counts

Author: Matt J. Jarvis, J. Sabater, N. J. Jackson, F. de Gasperin, Michael W. Wise, D. Engels, Emanuela Orrú, George K. Miley, Timothy W. Shimwell, E. Retana-Montenegro, R. Morganti, Wendy L. Williams, Marcus Brüggen, M. C. Toribio, Martin J. Hardcastle, T. J. Dijkema, Glenn J. White, Elizabeth K. Mahony, John Conway, Marijke Haverkorn, Leah K. Morabito, Isabella Prandoni, S. S. Sridhar, Philip Best, Jonathan T. L. Zwart, R. J. van Weeren, Chiara Ferrari, Gianfranco Brunetti, George Heald, Anna D. Kapińska, Heino Falcke, C. Tasse, I. van Bemmel, Torsten A. Enßlin, Huub Röttgering, Netherlands Institute for Radio Astronomy (ASTRON), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], University of Edinburgh, Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), University of Hertfordshire [Hatfield] (UH), Institute for Astronomy [Edinburgh] (IfA), SKA South Africa, Ska South Africa, 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), Jacobs University [Bremen], Joseph Louis LAGRANGE (LAGRANGE), 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, 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), Radboud university [Nijmegen], University of Oxford [Oxford], Centre d'études européennes et de politique comparée (CEE), Sciences Po (Sciences Po)-Centre National de la Recherche Scientifique (CNRS), Unité de Recherche sur les Maladies Infectieuses Tropicales Emergentes (URMITE), Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR48, INSB-INSB-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR48, INSB-INSB-Centre National de la Recherche Scientifique (CNRS), SLAC National Accelerator Laboratory (SLAC), Stanford University, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), 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), Centre d'études européennes et de politique comparée (Sciences Po, CNRS) (CEE), High Energy Astrophys. & Astropart. Phys (API, FNWI), Astronomy, bibliotheque, la., Leiden University, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, SUPA School of Physics and Astronomy [Edinburgh], University of Hamburg, University of Groningen [Groningen], INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Joint Institute for VLBI in Europe (JIVE ERIC), Chalmers University of Technology [Göteborg], Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Radboud University [Nijmegen], Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], University of Oxford, University of the Western Cape, International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia (UWA)-Government of Western Australia-Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), Institute of Cosmology and Gravitation [Portsmouth] (ICG), University of Portsmouth, Centre of Excellence for All-Sky Astrophysics (CAASTRO), Kapteyn Astronomical Institute [Groningen], The Open University [Milton Keynes] (OU), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), and University of Cape Town
Subjects: active [Galaxies], Hubble Deep Field, DEEP FIELD, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, Flux, Ecliptic pole, galaxies [Radio continuum], Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Surveys, X-RAY SURVEY, 01 natural sciences, [PHYS] Physics [physics], surveys, 610-MHZ SURVEY, 0103 physical sciences, DATA REDUCTION, Angular resolution, Source counts, ECLIPTIC POLE, Techniques:interferometric, Radio continuum:galaxies, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, radio continuum: galaxies, [PHYS]Physics [physics], Physics, 010308 nuclear & particles physics, 20 CM, SPECTRUM SOURCES, Astronomy and Astrophysics, BOOTES, LOFAR, FREQUENCY SKY SURVEY, 1ST SURVEY, Galaxy, Galaxies:active, techniques: interferometric, Space and Planetary Science, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, interferometric [Techniques], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics, METREWAVE-RADIO-TELESCOPE
Abstract: We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of the Bo\"otes field made at 130-169 MHz. This image is at least an order of magnitude deeper and 3-5 times higher in angular resolution than previously achieved for this field at low frequencies. The observations and data reduction, which includes full direction-dependent calibration, are described here. We present a radio source catalogue containing 6276 sources detected over an area of $19$\,deg$^2$, with a peak flux density threshold of $5\sigma$. As the first thorough test of the facet calibration strategy, introduced by van Weeren et al., we investigate the flux and positional accuracy of the catalogue. We present differential source counts that reach an order of magnitude deeper in flux density than previously achieved at these low frequencies, and show flattening at 150 MHz flux densities below 10 mJy associated with the rise of the low flux density star-forming galaxies and radio-quiet AGN., Comment: 29 pages, 27 figures, accepted for publication in MNRAS
Published: 2016

19. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

Author: Matteo Murgia, J. H. Croston, Huub Röttgering, Volker Heesen, Michael W. Wise, M. Brienza, Martin J. Hardcastle, Philip Best, Emanuela Orrú, Leith Godfrey, Aleksandar Shulevski, Elizabeth K. Mahony, Judith Ineson, Raffaella Morganti, Adam Stewart, Jeremy J. Harwood, Huib Intema, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Astronomy
Subjects: Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, galaxies: active, jets [galaxies], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, Parameter space, 01 natural sciences, Spectral line, X-shaped radio galaxy, 0103 physical sciences, 010303 astronomy & astrophysics, Equipartition theorem, acceleration of particles, Physics, radio continuum: galaxies, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, radiation mechanisms: non-thermal, galaxies: jets, non-thermal [radiation mechanisms], Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Magnetic field, galaxies [X-rays], X-rays: galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING
Abstract: Due to their steep spectra, low-frequency observations of FR II radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths has meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C452 and 3C223. We find that the morphology of 3C452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C452 and 2 for 3C223. We go on to discuss possible causes of these steeper than expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity., 13 pages, 5 figures, 10 tables. Accepted for publication in MNRAS
Published: 2016

20. Detection of non-thermal X-ray emission in the lobes and jets of Cygnus A

Author: Paul Nulsen, Ryan T. Duffy, Diana M Worrall, Mark Birkinshaw, Michael W. Wise, Martin J. Hardcastle, Brian R. McNamara, Daniela Huppenkothen, M. N. de Vries, Bradford Snios, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, individual:Cygnus A [galaxies], jets [galaxies], Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, galaxies [X-rays], 010104 statistics & probability, Space and Planetary Science, 0103 physical sciences, High Energy Physics::Experiment, 0101 mathematics, Cygnus A, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present a spectral analysis of the lobes and X-ray jets of Cygnus A, using more than 2 Ms of $\textit{Chandra}$ observations. The X-ray jets are misaligned with the radio jets and significantly wider. We detect non-thermal emission components in both lobes and jets. For the eastern lobe and jet, we find 1 keV flux densities of $71_{-10}^{+10}$ nJy and $24_{-4}^{+4}$ nJy, and photon indices of $1.72_{-0.03}^{+0.03}$ and $1.64_{-0.04}^{+0.04}$ respectively. For the western lobe and jet, we find flux densities of $50_{-13}^{+12}$ nJy and $13_{-5}^{+5}$ nJy, and photon indices of $1.97_{-0.10}^{+0.23}$ and $1.86_{-0.12}^{+0.18}$ respectively. Using these results, we modeled the electron energy distributions of the lobes as broken power laws with age breaks. We find that a significant population of non-radiating particles is required to account for the total pressure of the eastern lobe. In the western lobe, no such population is required and the low energy cutoff to the electron distribution there needs to be raised to obtain pressures consistent with observations. This discrepancy is a consequence of the differing X-ray photon indices, which may indicate that the turnover in the inverse-Compton spectrum of the western lobe is at lower energies than in the eastern lobe. We modeled the emission from both jets as inverse-Compton emission. There is a narrow region of parameter space for which the X-ray jet can be a relic of an earlier active phase, although lack of knowledge about the jet's electron distribution and particle content makes the modelling uncertain., Comment: 21 pages, 8 figures
Published: 2018

21. 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

22. The Cocoon Shocks of Cygnus A: Pressures and Their Implications for the Jets and Lobes

Author: Martin J. Hardcastle, Robert A. Laing, Paul Nulsen, Martijn de Vries, David Rafferty, Leith Godfrey, Mark Birkinshaw, Judith H. Croston, Ryan T. Duffy, Michael W. Wise, Brian R. McNamara, Chris L. Carilli, John McKean, Richard A. Perley, Alastair C. Edge, Bradford Snios, Andrew J. Young, Daniel E. Harris, William G. Mathews, Diana M Worrall, Ralph P. Kraft, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: individual (Cygnus A) [galaxies], Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Kinetic energy, 01 natural sciences, symbols.namesake, 0103 physical sciences, clusters: general [galaxies], Cygnus A, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Jet (fluid), Shock (fluid dynamics), 010308 nuclear & particles physics, Astronomy and Astrophysics, Static pressure, Ram pressure, galaxies [X-rays], Mach number, Space and Planetary Science, active [galaxies], symbols, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We use 2.0 Msec of Chandra observations to investigate the cocoon shocks of Cygnus A and some implications for its lobes and jet. Measured shock Mach numbers vary in the range 1.18-1.66 around the cocoon. We estimate a total outburst energy of $\simeq 4.7\times10^{60}\rm\ erg$, with an age of $\simeq 2 \times 10^{7}\rm\ yr$. The average postshock pressure is found to be $8.6 \pm 0.3 \times 10^{-10}\rm\ erg\ cm^{-3}$, which agrees with the average pressure of the thin rim of compressed gas between the radio lobes and shocks, as determined from X-ray spectra. However, average rim pressures are found to be lower in the western lobe than in the eastern lobe by $\simeq 20\%$. Pressure estimates for hotspots A and D from synchrotron self-Compton models imply that each jet exerts a ram pressure $\gtrsim$ 3 times its static pressure, consistent with the positions of the hotspots moving about on the cocoon shock over time. A steady, one-dimensional flow model is used to estimate jet properties, finding mildly relativistic flow speeds within the allowed parameter range. Models in which the jet carries a negligible flux of rest mass are consistent with with the observed properties of the jets and hotspots. This favors the jets being light, implying that the kinetic power and momentum flux are carried primarily by the internal energy of the jet plasma rather than by its rest mass., Comment: Accepted to ApJ, 15 pages, 7 figures, 4 tables
Published: 2018
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23. 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

24. 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

25. 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

26. 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

27. The LOFAR Two-metre Sky Survey: I. Survey description and preliminary data release

Author: Jeremy J. Harwood, Matthias Steinmetz, W. van Driel, Leah K. Morabito, Emanuela Orru, Magdalena Kunert-Bajraszewska, D. A. Rafferty, Isabella Prandoni, A. Horneffer, Huub Röttgering, R. J. van Weeren, Adam Deller, Subhash C. Mandal, J. Sabater, G. Calistro Rivera, M. Sipior, Daniel J. Smith, Frank P. Israel, Aleksandar Shulevski, John McKean, Marijke Haverkorn, D. Engels, Krzysztof T. Chyzy, Chiara Ferrari, P. van der Werf, Philip Best, J. B. R. Oonk, A. Drabent, Elizabeth K. Mahony, Raffaella Morganti, Marisa Brienza, Timothy W. Shimwell, Michael W. Wise, Annalisa Bonafede, Martin J. Hardcastle, Rainer Beck, S. S. Sridhar, Marcus Brüggen, Neal Jackson, Dominik J. Schwarz, M. A. Garrett, Cathy Horellou, Matthias Hoeft, J. A. Zensus, Gianfranco Brunetti, N. R. Mohan, George K. Miley, Andra Stroe, John Conway, Anna D. Kapińska, E. Retana-Montenegro, D. J. McKay, A. O. Clarke, I. van Bemmel, Glenn J. White, George Heald, Volker Heesen, Heino Falcke, Matt J. Jarvis, F. de Gasperin, Huib Intema, D. N. Hoang, Cyril Tasse, R. Pizzo, Eskil Varenius, S. Fröhlich, A. P. Mechev, D. Cseh, Wendy L. Williams, Rossella Cassano, Jonathan T. L. Zwart, T. J. Dijkema, Leiden Observatory [Leiden], Universiteit Leiden, Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Centre for Astrophysics Research, University of Hertfordshire [Hatfield] (UH), Netherlands Institute for Radio Astronomy (ASTRON), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Max-Planck-Institut für Radioastronomie (MPIFR), 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), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Istituto di Radioastronomia [Bologna] (IRA), Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory [Kraków], Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Radboud University [Nijmegen], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Oxford Astrophysics, University of Oxford, Department of Physics and Astronomy [Milton Keynes], The Open University [Milton Keynes] (OU), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), 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), 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), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Joseph Louis LAGRANGE (LAGRANGE), 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), Ruhr-Universität Bochum [Bochum], School of Physics and Astronomy [Southampton], University of Southampton, Joint Institute for VLBI in Europe (JIVE ERIC), Department of Earth and Space Sciences [Göteborg], The University of Western Australia (UWA), Torun Centre for Astronomy (TCfA), Nicolaus Copernicus University [Toruń], University of Oulu, National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Universität Bielefeld, Leibniz-Institut für Astrophysik Potsdam (AIP), European Southern Observatory (ESO), University of the Western Cape (UWC), European Project: 320745,EC:FP7:ERC,ERC-2012-ADG_20120216,RADIOLIFE(2013), Astronomy, Kapteyn Astronomical Institute, Universiteit Leiden [Leiden], Harvard University [Cambridge]-Smithsonian Institution, Radboud university [Nijmegen], 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), 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, 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), University of the Western Cape, High Energy Astrophys. & Astropart. Phys (API, FNWI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Smithsonian Institution-Harvard University [Cambridge], Istituto di Radioastronomia INAF, Jagiellonian University [Krakow] (UJ), Onsala Space Observatory, Istituto di Radioastronomia (IRA), 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), 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), and Tata Institute of Fundamental Research [Bombay] (TIFR)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Astronomy, radio continuum: general, FOS: Physical sciences, techniques: image processing, 01 natural sciences, Declination, Spectral line, RADIO RECOMBINATION LINES, techniques image processing, surveys, CALIBRATOR SURVEY, 0103 physical sciences, Calibration, radio-continuum, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, media_common, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], image processing [techniques], QUASAR SURVEY, Astronomy and Astrophysics, HERSCHEL-ATLAS, LOFAR, 1ST SURVEY, Galaxy, WIDE-FIELD, Space and Planetary Science, Sky, LUMINOSITY FUNCTION, general, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, general [radio continuum], CHANDRA OBSERVATIONS, Astrophysics - Instrumentation and Methods for Astrophysics, Right ascension, FOLLOW-UP, GALAXY CLUSTERS, surveys – catalogs – radio continuum: general – techniques: image processing, Geology, Noise (radio), catalogs, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5arcsec resolution images with a sensitivity of ~0.1mJy/beam and accomplish the main scientific aims of the survey which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Due to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully-automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25arcsec, typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45d00m00s to 57d00m00s)., Comment: 23 pages, 15 figures, 3 tables, accepted for publication in A&A
Published: 2017

28. Diffuse radio emission in MACS J0025.4-1222

Author: Anna M. M. Scaife, Michael W. Wise, A. O. Clarke, C. J. Riseley, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: MACS J0025.4-1222, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Radio relics, Intracluster medium, 0103 physical sciences, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy cluster, Physics, Giant Metrewave Radio Telescope, education.field_of_study, general [Radio continuum], 010308 nuclear & particles physics, Astronomy and Astrophysics, clusters: individual: MACS J0025.4-1222 [Galaxies], Astrophysics - Astrophysics of Galaxies, Redshift, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxies: clusters [X-rays], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Mergers of galaxy clusters are among the most energetic events in the Universe. These events have significant impact on the intra-cluster medium, depositing vast amounts of energy - often in the form of shocks - as well as heavily influencing the properties of the constituent galaxy population. Many clusters have been shown to host large-scale diffuse radio emission, known variously as radio haloes and relics. These sources arise as a result of electron (re-)acceleration in cluster-scale magnetic fields, although the processes by which this occurs are still poorly understood. We present new, deep radio observations of the high-redshift galaxy cluster MACS J0025.4$-$1222, taken with the GMRT at 325 MHz, as well as new analysis of all archival $Chandra$ X-ray observations. We aim to investigate the potential of diffuse radio emission and categorise the radio population of this cluster, which has only been covered previously by shallow radio surveys. We produce low-resolution maps of MACS J0025.4$-$1222 through a combination of uv-tapering and subtracting the compact source population. Radial surface brightness and mass profiles are derived from the $Chandra$ data. We also derive a 2D map of the ICM temperature. For the first time, two sources of diffuse radio emission are detected in MACS J0025.4$-$1222, on linear scales of several hundred kpc. Given the redshift of the cluster and the assumed cosmology, these sources appear to be consistent with established trends in power scaling relations for radio relics. The X-ray temperature map presents evidence of an asymmetric temperature profile and tentative identification of a temperature jump associated with one relic. We classify the pair of diffuse radio sources in this cluster as a pair of radio relics, given their consistency with scaling relations, location toward the cluster outskirts, and the available X-ray data., 20 pages, 15 figures, accepted for publication in A&A
Published: 2017

29. 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

30. LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra

Author: Aris Karastergiou, Michael W. Wise, Gianni Bernardi, Heino Falcke, L. Cerrigone, D. Engels, Michel Tagger, Simona Vegetti, Anna Nelles, R. Morganti, John D. Swinbank, Leith Godfrey, George Heald, I. van Bemmel, E. Juette, P. Maat, Sera Markoff, V. I. Kondratiev, Léon V. E. Koopmans, Huib Intema, Adam Deller, H. Munk, J. W. Broderick, Marcus Brüggen, R. Blaauw, J. Sluman, M. Iacobelli, R. J. van Weeren, Roberto Pizzo, Philip Best, A. J. van der Horst, D. McKay-Bukowski, Wilfred Frieswijk, M. Pandey-Pommier, Martin J. Hardcastle, M. Pietka, Aleksandar Shulevski, Rainer Beck, Satyendra Thoudam, M. Serylak, Matthias Steinmetz, Anna M. M. Scaife, Emanuela Orrú, Antonia Rowlinson, D. D. Mulcahy, Sarod Yatawatta, H. Paas, Adam Stewart, S. Duscha, I. M. Avruch, Frank Breitling, B. Ciardi, John McKean, H. J. A. Röttgering, R. C. Vermeulen, Oleg Smirnov, Olaf Wucknitz, W. Reich, Gottfried Mann, F. de Gasperin, P. Zarka, M. Kuniyoshi, D. Rafferty, Martin Bell, Richard Fallows, James M. Anderson, G. Kuper, Mark J. Bentum, M. A. Garrett, J.-M. Grießmeier, Matthias Hoeft, Christian Vocks, M. P. van Haarlem, M. C. Toribio, A. G. Polatidis, J. van Leeuwen, Annalisa Bonafede, Rebecca McFadden, Netherlands Institute for Radio Astronomy (ASTRON), SRON Netherlands Institute for Space Research (SRON), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), University of Hertfordshire [Hatfield] (UH), Department of Astronomy and Astrophysics [PennState], Pennsylvania State University (Penn State), Penn State System-Penn State System, Department of Atmospheric and Planetary Sciences [Hampton] (APS), Hampton University, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Université de Tours (UT), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of Southampton, 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, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Institute of Mathematical and Physical Sciences, Leiden Observatory [Leiden], Universiteit Leiden, 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), 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), Joint Institute for VLBI in Europe (JIVE ERIC), Department of Pure Mathematics and Mathematical Statistics (DPMMS), Faculty of mathematics Centre for Mathematical Sciences [Cambridge] (CMS), University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Ruhr-Universität Bochum [Bochum], Oxford Astrophysics, University of Oxford, Max-Planck-Institut für Radioastronomie (MPIFR), University of Oulu, University of Groningen, Groningen, Netherlands, 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), Australia Telescope National Facility (ATNF), School of Physics and Astronomy [Southampton], Department of Physics and Astronomy [South Africa], University of the Western Cape (UWC), Rhodes University, Grahamstown, 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], Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, 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), European Project: 320745,EC:FP7:ERC,ERC-2012-ADG_20120216,RADIOLIFE(2013), Astronomy, McKean, J.P., Godfrey, L.E.H., Vegetti, S., Wise, M.W., Morganti, R., Hardcastle, M.J., Rafferty, D., Anderson, J., Avruch, I.M., Beck, R., Bell, M.E., van Bemmel, I., Bentum, M.J., Bernardi, G., Best, P., Blaauw, R., Bonafede, A., Breitling, F., Broderick, J.W., Brüggen, M., Cerrigone, L., Ciardi, B., de Gasperin, F., Deller, A., Duscha, S., Engels, D., Falcke, H., Fallows, R.A., Frieswijk, W., Garrett, M.A., Grießmeier, J.M., van Haarlem, M.P., Heald, G., Hoeft, M., van der HorstA.J., null, Iacobelli, M., Interna, H., Juette, E., Karastergiou, A., Kondratiev, V.I., Koopmans, L.V.E., Kuniyoshi, M., Kuper, G., van Leeuwen, J., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., Mulcahy, D.D., Munk, H., Nelles, A., Orru, E., Paas, H., Pandey-Pommier, M., Pietka, M., Pizzo, R., Polatidis, A.G., Reich, W., Rottgering, H.J.A., Rowlinson, A., Scaife, A.M.M., Serylak, M., Shulevski, A., Sluman, J., Smirnov, O., Steinmetz, M., Stewart, A., Swinbank, J., Tagger, M., Thoudam, S., Toribio, M.C., Vermeulen, R., Vocks, C., van Weeren, R.J., Wucknitz, O., Yatawatta, S., Zarka, P., High Energy Astrophys. & Astropart. Phys (API, FNWI), 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), Radboud university [Nijmegen], Universiteit Leiden [Leiden], 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), University of Oxford [Oxford], 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), University of the Western Cape, Smithsonian Institution-Harvard University [Cambridge], ITA, GBR, FRA, DEU, NLD, Université de Tours, 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), and Harvard University [Cambridge]-Smithsonian Institution
Subjects: Radio galaxy, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio continuum: galaxie, Spectral line, Radio spectrum, Radio continuum: galaxies, Galaxies: active: individual: Cygnus A, X-shaped radio galaxy, 0103 physical sciences, Cygnus A, 010303 astronomy & astrophysics, Physics, Spectral index, EWI-27659, 010308 nuclear & particles physics, LOBES, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies [radio continuum], GALAXIES, METIS-321690, RESOLUTION, Space and Planetary Science, HOT-SPOTS, GAS, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, ARRAY, IR-103274
Abstract: The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ~3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self absorption models are able to describe the low-frequency spectral shape of the hotspots, however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic., Comment: 9 pages, 3 figures, accepted for publication in MNRAS
Published: 2016

31. The duty cycle of the radio mode feedback

Author: Michael W. Wise, Paul Nulsen, H. J. A. Röttgering, Laura Birzan, Brian R. McNamara, and D. A. Rafferty
Subjects: Physics, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, Flux, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Cooling flow, Galaxy, Luminosity, Space and Planetary Science, Duty cycle, Intracluster medium, Galaxy cluster
Abstract: The Chandra X-ray Observatory has revealed X-ray bubbles in the intracluster medium (ICM) of many nearby clusters, which are thought to be created by the central active galactic nucleus (AGN). However, the duty cycle of such AGN outbursts is not well understood. In order to further understand how cooling is balanced by bubble heating we studied complete samples of cooling flow clusters (from the Brightest 55 clusters of galaxies sample, B55, and the HIghest X-ray FLUx Galaxy Cluster Sample, HIFLUGCS). We found that there is a radio luminosity cut-off of 2.5×1030 erg s-1 Hz-1 for the cooling flow clusters. Furthermore, we find a duty cycle for radio mode feedback, the fraction of time that a system possesses bubbles inflated by its central radio source, of ≳ 69 % for the B55 sample and ≳ 63 % for the HIFLUGCS sample. These duty cycles are lower limits since some bubbles are likely missed in existing images. We used simulations to constrain the bubble power that might be present and remain undetected in the cooling flow systems without detected bubbles. Among theses systems, almost all could have significant bubble power. Therefore, our results imply that the duty cycle of AGN outbursts with the potential to heat the gas significantly in cooling flow clusters is at least 60% and could approach 100 %.
Published: 2013

32. A deep Chandra observation of the active galactic nucleus outburst and merger in Hickson compact group 62

Author: W. N. Brandt, Michael W. Wise, D. A. Rafferty, Laura Birzan, H. J. A. Röttgering, Paul Nulsen, Brian R. McNamara, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Active galactic nucleus, Metallicity, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Electron, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Luminosity, Compact group, Space and Planetary Science, Radiative transfer, Surface brightness, Astrophysics::Galaxy Astrophysics
Abstract: We report on an analysis of new Chandra data of the galaxy group HCG 62, well known for possessing cavities in its intragroup medium (IGM) that were inflated by the radio lobes of its central active galactic nucleus (AGN). With the new data, a factor of 3 deeper than previous Chandra data, we re-examine the energetics of the cavities and determine new constraints on their contents. We confirm that the ratio of radiative to mechanical power of the AGN outburst that created the cavities is less than 10− 4, among the lowest of any known cavity system, implying that the relativistic electrons in the lobes can supply only a tiny fraction of the pressure required to support the cavities. This finding implies additional pressure support in the lobes from heavy particles (e.g. protons) or thermal gas. Using spectral fits to emission in the cavities, we constrain any such volume-filling thermal gas to have a temperature kT ≳ 4.3 keV. For the first time, we detect X-ray emission from the central AGN, with a luminosity of L2--10keV=(1.1±0.4)×1039 erg s− 1 and properties typical of a low-luminosity AGN. Finally, we report evidence for a recent merger from the surface brightness, temperature and metallicity structure of the IGM.
Published: 2013

33. Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere

Author: Y. Tang, Anna M. M. Scaife, Steve Rawlings, Aris Karastergiou, Michael W. Wise, Harvey Butcher, B. Ciardi, S. Duscha, V. N. Pandey, Gianni Bernardi, John McKean, Charlotte Sobey, Emanuela Orrú, Chiara Ferrari, M. Kuniyoshi, H. Munk, Marcus Brüggen, Michael Kramer, Cyril Tasse, J. W. Broderick, E. de Geus, Ashish Asgekar, Jason W. T. Hessels, F. de Gasperin, Matthias Hoeft, George Heald, L. Kuiper, A. P. Schoenmakers, P. Maat, R. H. van de Brink, Sera Markoff, Dipanjan Mitra, Philip Best, G. Wright, Ralph A. M. J. Wijers, J. de Plaa, Heino Falcke, V. I. Kondratiev, Rahul Basu, A. Noutsos, T. Coenen, Benjamin Stappers, Michel Tagger, Frank Breitling, Giulia Macario, Rob Fender, Rene C. Vermeulen, Michael R. Bell, F. Batejat, A. Alexov, Marco Iacobelli, H. Paas, Sarod Yatawatta, Patrick Weltevrede, Tim Hassall, R. J. van Weeren, W. Reich, M. Pilia, Laura Birzan, W. Hermsen, Evan Keane, Aleksandar Shulevski, Mark J. Bentum, M. Serylak, Martin Bell, Annalisa Bonafede, J. van Leeuwen, A. Horneffer, Jochen Eislöffel, Maaijke Mevius, H. J. A. Röttgering, A. G. Polatidis, R. Morganti, I. M. Avruch, S. ter Veen, A. W. Gunst, Olaf Wucknitz, Matthias Steinmetz, M. Pandey-Pommier, K. Zagkouris, J. Sluman, Roberto Pizzo, Jean-Mathias Grießmeier, G. Kuper, Philippe Zarka, Joanna M. Rankin, M. A. Garrett, James Miller-Jones, Wilfred Frieswijk, Hermsen, W., Hessels, J.W.T., Kuiper, L., Van Leeuwen, J., Mitra, D., De Plaa, J., Rankin, J.M., Stappers, B.W., Wright, G.A.E., Basu, R., Alexov, A., Coenen, T., Grießmeier, J.-M., Hassall, T.E., Karastergiou, A., Keane, E., Kondratiev, V.I., Kramer, M., Kuniyoshi, M., Noutsos, A., Serylak, M., Pilia, M., Sobey, C., Weltevrede, P., Zagkouris, K., Asgekar, A., Avruch, I.M., Batejat, F., Bell, M.E., Bell, M.R., Bentum, M.J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Butcher, H.R., Ciardi, B., Duscha, S., Eislöffel, J., Falcke, H., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., De Gasperin, F., De Geus, E., Gunst, A.W., Heald, G., Hoeft, M., Horneffer, A., Iacobelli, M., Kuper, G., Maat, P., Macario, G., Markoff, S., McKean, J.P., Mevius, M., Miller-Jones, J.C.A., Morganti, R., Munk, H., Orrú, E., Paas, H., Pandey-Pommier, M., Pandey, V.N., Pizzo, R., Polatidis, A.G., Rawlings, S., Reich, W., Röttgering, H., Scaife, A.M.M., Schoenmakers, A., Shulevski, A., Sluman, J., Steinmetz, M., Tagger, M., Tang, Y., Tasse, C., Ter Veen, S., Vermeulen, R., Van De Brink, R.H., Van Weeren, R.J., Wijers, R.A.M.J., Wise, M.W., Wucknitz, O., Yatawatta, S., Zarka, P., SRON Netherlands Institute for Space Research (SRON), University of Amsterdam [Amsterdam] (UvA), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), University of Vermont [Burlington], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Astronomy Centre, University of Sussex, Space Telescope Science Institute (STSci), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), 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), Oxford Astrophysics, University of Oxford, Centre for Astrophysics and Supercomputing, Swinburne University of Technology [Melbourne], Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], University of Southampton, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, University of Edinburgh, Leiden Observatory [Leiden], Universiteit Leiden, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Thüringer Landessternwarte Tautenburg (TLS), Radboud University [Nijmegen], Joseph Louis LAGRANGE (LAGRANGE), 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), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Medstar Research Institute, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], 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), School of Physics and Astronomy [Southampton], SKA South Africa, Ska South Africa, 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), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, ANR-09-JCJC-0001,OPALES(2009), Kapteyn Astronomical Institute, Astronomy, 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), University of Oxford [Oxford], Harvard University [Cambridge]-Smithsonian Institution, Universiteit Leiden [Leiden], Radboud university [Nijmegen], 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, 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), 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), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Electromagnetic field, POLARIZATION, Electromagnetic spectrum, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, FOS: Physical sciences, Magnetosphere, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, EMPIRICAL-THEORY, 01 natural sciences, Binary pulsar, Pulsar, Millisecond pulsar, 0103 physical sciences, 010306 general physics, XMM-NEWTON OBSERVATIONS, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, DRIFTING SUBPULSES, Multidisciplinary, B0943+10, Polarization (waves), GAMMA-RAY, [SDU]Sciences of the Universe [physics], 13. Climate action, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, RADIATION, EMISSION, Astrophysics - High Energy Astrophysical Phenomena, PHOTON IMAGING CAMERA, POWERED PULSARS, Radio wave
Abstract: Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out to the edges of the magnetosphere. Detecting correlated mode changes in the multi-wavelength emission is therefore key to understanding the physical relationship between these emission sites. Through simultaneous observations, we have detected synchronous switching in the radio and X-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio 'bright' mode, the X-rays show only an un-pulsed, non-thermal component. Conversely, when the pulsar is in a radio 'quiet' mode, the X-ray luminosity more than doubles and a 100%-pulsed thermal component is observed along with the non-thermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories., Paper published in Science including supplementary material
Published: 2013

34. The duty cycle of radio-mode feedback in complete samples of clusters

Author: Laura Birzan, Brian R. McNamara, H. J. A. Röttgering, Rupal Mittal, D. A. Rafferty, Michael W. Wise, Paul Nulsen, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Cooling flow, Galaxy, Luminosity, Space and Planetary Science, Duty cycle, Intracluster medium, Astrophysics::Galaxy Astrophysics, Galaxy cluster, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The Chandra X-ray Observatory has revealed X-ray bubbles in the intracluster medium (ICM) of many nearby cooling flow clusters. The bubbles trace feedback that is thought to couple the central active galactic nucleus (AGN) to the ICM, helping to stabilize cooling flows and govern the evolution of massive galaxies. However, the prevalence and duty cycle of such AGN outbursts is not well understood. To this end, we study how cooling is balanced by bubble heating for complete samples of clusters (the Brightest 55 clusters of galaxies, hereafter B55, and the HIghest X-ray FLUx Galaxy Cluster Sample, HIFLUGCS). We find that the radio luminosity of the central galaxy only exceeds 2.5 x 10^30 erg s^-1 Hz^-1 in cooling flow clusters. This result implies a connection between the central radio source and the ICM, as expected if AGN feedback is operating. Additionally, we find a duty cycle for radio mode feedback, the fraction of time that a system possesses bubbles inflated by its central radio source, of > 69 per cent for B55 and > 63 per cent for HIFLUGCS. These duty cycles are lower limits since some bubbles are likely missed in existing images. We used simulations to constrain the bubble power that might be present and remain undetected in the cooling flow systems without detected bubbles. Among theses systems, almost all could have significant bubble power. Therefore, our results imply that the duty cycle of AGN outbursts with the potential to heat the gas significantly in cooling flow clusters is at least 60 per cent and could approach 100 per cent., Accepted to MNRAS, 24 pages, 5 figures
Published: 2012

35. LOFAR and APERTIF Surveys of the Radio Sky: Probing Shocks and Magnetic Fields in Galaxy Clusters

Author: Michael W. Wise, George H. Miley, Emanuela Orrú, Reinout J. van Weeren, Tom Oosterloo, Francesco de Gasperin, Matt J. Jarvis, John Conway, Marc Verheijen, David Rafferty, Huub Röttgering, Bas van der Tol, John McKean, Louise Ker, George Heald, Cyril Tasse, Glenn J. White, Roberto Pizzo, Krzysztof T. Chyzy, Matthias Hoeft, F. Batejat, Chiara Ferrari, Raffaella Morganti, Gianfranco Brunetti, Jose Afonso, Marcus Brüggen, Giulia Macario, Annalisa Bonafede, Ilse van Bemmel, Philip Best, A. Shulevski, Peter Barthel, Neal Jackson, Marijke Haverkorn, Matt Lehnert, Röttgering, Huub, Afonso, Jose, Barthel, Peter, Batejat, Fabien, Best, Philip, Bonafede, Annalisa, Brüggen, Marcu, Brunetti, Gianfranco, Chyzy, Krzysztof, Conway, John, De Gasperin, Francesco, Ferrari, Chiara, Haverkorn, Marijke, Heald, George, Hoeft, Matthia, Jackson, Neal, Jarvis, Matt, Ker, Louise, Lehnert, Matt, Macario, Giulia, McKean, John, Miley, George, Morganti, Raffaella, Oosterloo, Tom, Orrù, Emanuela, Pizzo, Roberto, Rafferty, David, Shulevski, Alexander, Tasse, Cyril, van Bemmel, Ilse, van der Tol, Ba, van Weeren, Reinout, Verheijen, Marc, White, Glenn, Wise, Michael, Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 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, and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Electromagnetic spectrum, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxie, Radio telescope, 0103 physical sciences, galaxies, Cluster (physics), clusters, cluster, 010303 astronomy & astrophysics, Galaxy cluster, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, media_common, Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, general, intracluster medium, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Galaxy, galaxies [radio continuum], Sky, radio telescope, Space and Planetary Science, Radio frequency, radio continuum: galaxie, radio telescopes, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: At very low frequencies, the new pan-European radio telescope LOFAR is opening the last unexplored window of the electromagnetic spectrum for astrophysical studies. The revolutionary APERTIF phased arrays that are about to be installed on the Westerbork radio telescope (WSRT) will dramatically increase the survey speed for the WSRT. Combined surveys with these two facilities will deeply chart the northern sky over almost two decades in radio frequency from \sim 15 up to 1400 MHz. Here we briefly describe some of the capabilities of these new facilities and what radio surveys are planned to study fundamental issues related the formation and evolution of galaxies and clusters of galaxies. In the second part we briefly review some recent observational results directly showing that diffuse radio emission in clusters traces shocks due to cluster mergers. As these diffuse radio sources are relatively bright at low frequencies, LOFAR should be able to detect thousands of such sources up to the epoch of cluster formation. This will allow addressing many question about the origin and evolution of shocks and magnetic fields in clusters. At the end we briefly review some of the first and very preliminary LOFAR results on clusters., Comment: 11 pages, 2 figures, Invited talk at the conference "Diffuse Relativistic Plasmas", Bangalore, 1-4 March 2011; in press for publication in special issue of Journal of Astrophysics and Astronomy
Published: 2016

36. Low-radio-frequency eclipses of the redback pulsar J2215+5135 observed in the image plane with LOFAR

Author: Michael Kramer, S. ter Veen, Jean-Mathias Grießmeier, J. van Leeuwen, Tim Hassall, P.G. Jonker, Rudy Wijnands, M. Pietka, Ralph A. M. J. Wijers, Adam Stewart, L. H. A. Scheers, John D. Swinbank, Rob Fender, M. Kuniyoshi, Ben Stappers, M. Serylak, Heino Falcke, J. W. Broderick, Jochen Eislöffel, D. Carbone, Martin Bell, Michael W. Wise, Tim D. Staley, Sera Markoff, Antonia Rowlinson, Y. Cendes, A. J. van der Horst, Rene P. Breton, Jason W. T. Hessels, Gijs Molenaar, Stephane Corbel, Philippe Zarka, Casey J. Law, High Energy Astrophys. & Astropart. Phys (API, FNWI), Faculty of Science, University of Southampton, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Netherlands Institute for Radio Astronomy (ASTRON), Oxford Astrophysics, University of Oxford [Oxford], The George Washington University (GW), 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)-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), Thüringer Landessternwarte Tautenburg (TLS), 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Max-Planck-Institut für Radioastronomie (MPIFR), 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-10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2010), ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), European Project: 247295,EC:FP7:ERC,ERC-2009-AdG,AARTFAAC(2010), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), University of Oxford, 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), 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), Radboud University [Nijmegen], 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), Database Architectures, George Washington University (GW), 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), ANR-10-LABX-0023,Labex UnivEarthS, and ANR-11-IDEX-0005-02/10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2011)
Subjects: media_common.quotation_subject, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, general [Pulsars], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Radio telescope, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, individual: PSR J2215+5135 [Pulsars], Keywords: binaries: eclipsing, pulsars: individual: PSR J2215+5135, Astrophysics::Solar and Stellar Astrophysics, radio continuum: stars, 010303 astronomy & astrophysics, binaries: eclipsing, media_common, Eclipse, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, eclipsing [Binaries], Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Interferometry, Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, stars [Radio continuum], Radio frequency, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The eclipses of certain types of binary millisecond pulsars (i.e. `black widows' and `redbacks') are often studied using high-time-resolution, `beamformed' radio observations. However, they may also be detected in images generated from interferometric data. As part of a larger imaging project to characterize the variable and transient sky at radio frequencies, 9 pages, 4 figures, 4 tables, accepted for publication in MNRAS
Published: 2016

37. Cold, clumpy accretion onto an active supermassive black hole

Author: Stefi A. Baum, Francoise Combes, Andrew C. Fabian, Grant R. Tremblay, Brian R. McNamara, G. Mark Voit, Michael McDonald, Megan Donahue, Michael W. Wise, Anaëlle Maury, Stephen Hamer, Jeremy S. Sanders, P. Salome, Alastair C. Edge, Yuan Li, Malcolm N. Bremer, Louise O. V. Edwards, Helen Russell, Tracy E. Clarke, Raymond Oonk, Timothy A. Davis, Roberto Galván-Madrid, Alice C. Quillen, Christopher P. O'Dea, C. Megan Urry, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / 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), 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), 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), Collège de France - Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Laboratoire AIM, and Université Paris Diderot - Paris 7 ( UPD7 ) -Centre d'Etudes de Saclay
Subjects: Active galactic nucleus, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Mass deficit, astro-ph.GA, Astrophysics::High Energy Astrophysical Phenomena, Galaxies and clusters, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, General Relativity and Quantum Cosmology, Interstellar medium, M–sigma relation, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, QB, Physics, astro-ph.HE, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, Multidisciplinary, 010308 nuclear & particles physics, Astronomy, Astrophysics - Astrophysics of Galaxies, Black hole, 13. Climate action, Intermediate-mass black hole, Astrophysics of Galaxies (astro-ph.GA), Stellar black hole, Spin-flip, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena
Abstract: Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds - a departure from the "hot mode" accretion model - although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z=0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities can precipitate from this hot gas, producing a rain of cold clouds that fall toward the galaxy's centre, sustaining star formation amid a kiloparsec-scale molecular nebula that inhabits its core. The observations show that these cold clouds also fuel black hole accretion, revealing "shadows" cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole in the galaxy centre, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it., Published in the June 9th, 2016 issue of Nature
Published: 2016

38. Discovering the sky at the longest wavelengths (DSL)

Author: Julien N. Girard, Marc Klein-Wolt, Shufan Wu, Jianhua Zheng, Mark J. Bentum, Ji Wu, Michael W. Wise, Tao An, Hans de Haan, Linjie Chen, Jian Guo, Arnold van Ardenne, Léon V. E. Koopmans, Xiaoyu Hong, Gert H. Kruithof, Eberhard Gill, Xuelei Chen, Heino Falcke, Baptiste Cecconi, Maohai Huang, Wen Chen, Philippe Zarka, Leonid I. Gurvits, Albert-Jan Boonstra, Jingye Yan, Hanna Rothkaehl, M. A. Garrett, Netherlands Institute for Radio Astronomy (ASTRON), Shanghai Astronomical Observatory (SHAO), Space Research Center, Polish Academy of Sciences (Warsaw), National Space Science Centre (NSSC), Astronomy Department, Radboud University Nijmegen (Radboud), National Astronomical Observatoires-CAS, Space Institute Faculty of Aerospace (TU Delft), Shanghai Engineering Centre for Microsatellites (SECM), Joint Institute for VLBI in Europe (JIVE), University of Twente, Kapteyn Astronomical Institute, University of Groningen, 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), Physique des plasmas, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / 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-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Stip BV
Subjects: 010504 meteorology & atmospheric sciences, Frequency band, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Electromagnetic interference, law.invention, Telescope, EWI-27080, Observatory, law, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, LOFAR, Physics::Space Physics, METIS-318462, Space Science, Ionosphere, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], IR-101030, Radio astronomy
Abstract: The radio sky at frequencies below ~30 MHz is virtually unobservable from Earth due to ionospheric disturbances and the opaqueness of the ionosphere below ~10MHz, and also due to strong terrestrial radio interference. Deploying a radio observatory in space would open up this largely unexplored frequency band for science in astronomy, cosmology, geophysics, and space science. A Chinese-European team is proposing an ultra long wavelength (ULW) radio interferometer mission DSL (Discovering the Sky at the Longest Wavelengths). The proposed radio interferometer will be deployed in low-altitude lunar orbit, exploiting the radio quietness of the lunar far side. DSL will consist of a mother-spacecraft for data transport and control, plus eight small micro-satellites each equipped with three orthogonal dipoles. These satellites form a virtual distributed observatory with adjustable baselines, allowing different scientific observation strategies. The satellites are configured in a flexible quasi-linear array in nearly identical orbits, guaranteeing low relative drift rates. Short orbital periods and orbit precession ensure quick filling of the interferometric spatial frequency (u, v, w) space, enabling high quality imaging. The science themes considered for the DSL mission include pioneering studies of the unknown and exploratory science such as the search for signatures of the cosmological Dark Ages, complementing current (e.g. LOFAR) and future SKA telescope searches; full-sky continuum survey of discrete sources, including ultra-steep spectrum extragalactic sources, pulsars, and transients (galactic and extragalactic); full-sky map of continuum diffuse emission; solar-terrestrial physics, planetary sciences, and cosmic ray physics. The main frequency band covered is 1-30 MHz extending down to 0.1 MHz, and up to about 50 MHz for cross-referencing with ground-based instruments. DSL will support a variety of observational modes, including broad-band spectral analysis for Dark Ages, radio interferometric cross-correlations for imaging, and flexible raw data downlink capability. Data processing will be performed at radio astronomy science data centres in Europe and China.
Published: 2016

39. LBCS: The LOFAR Long-Baseline Calibrator Survey

Author: Rebecca McFadden, G. M. Loose, J. van Leeuwen, J. Schaap, N. J. Vermaas, M. P. van Haarlem, Philip Best, M. Sipior, E. de Geus, E. Juette, D. Engels, Sarod Yatawatta, J. Moldón, George Heald, Anna M. M. Scaife, C. Vocks, F. Breitling, M. Iacobelli, L. Cerrigone, D. D. Mulcahy, H. J. A. Röttgering, Matthias Hoeft, John D. Swinbank, Jean-Mathias Griessmeier, W. Reich, P. Maat, James M. Anderson, M. A. Garrett, Amitpal S. Tagore, I. van Bemmel, J. Sluman, Roberto Pizzo, R. Vermeulen, Marcus Brüggen, Satyendra Thoudam, Aleksandar Shulevski, R. Blaauw, M. C. Toribio, Emanuela Orrú, A. Horneffer, R. J. van Weeren, W. N. Brouw, Martin Bell, M. Avruch, Michael W. Wise, Jörg R. Hörandel, D. McKay-Bukowski, Jochen Eislöffel, Gerard H. Kuper, P. Zarka, Adam Deller, A. Drabent, Mark J. Bentum, Arthur Corstanje, Dominik J. Schwarz, Matthias Steinmetz, F. de Gasperin, Richard Fallows, H. Munk, A. G. Polatidis, Tobia Carozzi, Annalisa Bonafede, S. ter Veen, Leah K. Morabito, A. W. Gunst, John Conway, Anna D. Kapińska, Huib Intema, Heino Falcke, J. W. Broderick, M. Pandey-Pommier, Neal Jackson, Antonia Rowlinson, John McKean, Michiel A. Brentjens, B. Ciardi, Eskil Varenius, O. Wucknitz, M. Kuniyoshi, School of Physics and Astronomy [Manchester], University of Manchester [Manchester], Netherlands Institute for Radio Astronomy (ASTRON), Departament d'Astronomia i Meteorologia [Barcelona], Universitat de Barcelona (UB), Onsala Space Observatory, Dept. of Radio and Space Science, Chalmers University of Technology, Chalmers University of Technology [Göteborg], ARC Centre of Excellence for Autonomous Systems (CAS), University of Technology Sydney (UTS), Swedish Institute of Space Physics [Uppsala] (IRF), Department of Pure Mathematics and Mathematical Statistics (DPMMS), Faculty of mathematics Centre for Mathematical Sciences [Cambridge] (CMS), University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Department of Astrophysics [Nijmegen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen]-Radboud university [Nijmegen], GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Newcastle University [Newcastle], Joint Institute for VLBI in Europe (JIVE ERIC), University of Hamburg, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Leibniz-Institut für Astrophysik Potsdam (AIP), Oxford Astrophysics, University of Oxford [Oxford], University of Southampton, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], University of Edinburgh, Radboud university [Nijmegen], Thüringer Landessternwarte Tautenburg (TLS), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), 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), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), 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)-Centre National d’Études Spatiales [Paris] (CNES), Max-Planck-Institut für Radioastronomie (MPIFR), Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], National Astronomical Observatory of Japan (NAOJ), Health Service Executive [Dublin] (HSE), Aalborg University [Denmark] (AAU), 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-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Astrophysikalisches Institut Potsdam (AIP), Princeton University, SRON Netherlands Institute for Space Research (SRON), 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), European Project: 283393,EC:FP7:INFRA,FP7-INFRASTRUCTURES-2011-1,RADIONET3(2012), High Energy Astrophys. & Astropart. Phys (API, FNWI), Radboud University [Nijmegen]-Radboud University [Nijmegen], Universiteit Leiden, University of Oxford, Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), 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), Jackson, N., Tagore, A., Deller, A., Moldón, J., Varenius, E., Morabito, L., Wucknitz, O., Carozzi, T., Conway, J., Drabent, A., Kapinska, A., Orrù, E., Brentjens, M., Blaauw, R., Kuper, G., Sluman, J., Schaap, J., Vermaas, N., Iacobelli, M., Cerrigone, L., Shulevski, A., Ter Veen, S., Fallows, R., Pizzo, R., Sipior, M., Anderson, J., Avruch, I.M., Bell, M.E., Van Bemmel, I., Bentum, M.J., Best, P., Bonafede, A., Breitling, F., Broderick, J.W., Brouw, W.N., Brüggen, M., Ciardi, B., Corstanje, A., De Gasperin, F., De Geus, E., Eislöffel, J., Engels, D., Falcke, H., Garrett, M.A., Grießmeier, J.M., Gunst, A.W., Van Haarlem, M.P., Heald, G., Hoeft, M., Hörandel, J., Horneffer, A., Intema, H., Juette, E., Kuniyoshi, M., Van Leeuwen, J., Loose, G.M., Maat, P., McFadden, R., McKay-Bukowski, D., McKean, J.P., Mulcahy, D.D., Munk, H., Pandey-Pommier, M., Polatidis, A.G., Reich, W., Röttgering, H.J.A., Rowlinson, A., Scaife, A.M.M., Schwarz, D.J., Steinmetz, M., Swinbank, J., Thoudam, S., Toribio, M.C., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wise, M.W., Yatawatta, S., Zarka, P., and Astronomy
Subjects: Coherence time, media_common.quotation_subject, Astronomy, interferometers [instrumentation], galaxies: active, EWI-27445, Flux, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Radio continuum: galaxie, law.invention, Instrumentation: interferometer, Telescope, surveys, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Range (statistics), Astronomy, Astrophysics and Cosmology, Survey, instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), media_common, radio continuum: galaxies, Instrumentation:interferometers- Techniques:interferometric - Surveys - Galaxies:active -Radio continuum:galaxies, 020206 networking & telecommunications, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Geodesy, Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Square degree, interferometric [techniques], METIS-319490, Sky, Space and Planetary Science, techniques: interferometric, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), active [galaxies], Environmental science, Astrophysics - Instrumentation and Methods for Astrophysics, IR-102283, Coherence (physics)
Abstract: (abridged). We outline LBCS (the LOFAR Long-Baseline Calibrator Survey), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (50-100mJy) at frequencies around 110--190~MHz on scales of a few hundred mas. At least for the 200--300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas -- typically a few degrees -- around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200--600~km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per square degree. Coherence times decrease from 1--3 minutes on 200-km baselines to about 1 minute on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 minutes, is seen on the DE609 baseline, which at 227km is close to being the shortest. We see median coherence times of between 80 and 110 seconds on the four longest baselines (580--600~km), and about 2 minutes for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 degree., Accepted by Astronomy & Astrophysics. Error in figure 6 corrected
Published: 2016

40. LOFAR MSSS: detection of a low-frequency radio transient in 400 h of monitoring of the North Celestial Pole

Author: Rebecca McFadden, Martin Bell, Sera Markoff, G. Kokotanekov, R. J. van Weeren, D. McKay-Bukowski, James M. Anderson, Jason W. T. Hessels, Peter G. Jonker, Ralph A. M. J. Wijers, H. Munk, Casey J. Law, Frank Breitling, B. Scheers, Marcus Brüggen, M. C. Toribio, A. Horneffer, George Heald, M. A. Garrett, Aris Karastergiou, Luke Pratley, Rudy Wijnands, Y. Cendes, F. de Gasperin, A. Alexov, Michael W. Wise, Gianni Bernardi, Jörg R. Hörandel, B. Ciardi, M. Kuniyoshi, James Miller-Jones, J. van Leeuwen, T. Munoz-Darias, Aleksandar Shulevski, John McKean, J.-M. Grießmeier, John D. Swinbank, Jochen Eislöffel, P. Maat, Cyril Tasse, Wilfred Frieswijk, M. J. Norden, J. W. Broderick, A. G. Polatidis, Arthur Corstanje, T E Hassall, Heino Falcke, Harvey Butcher, E. de Geus, V. I. Kondratiev, E. Juette, Anna M. M. Scaife, M. Pandey-Pommier, Benjamin Stappers, H. Paas, A. W. Gunst, I. M. Avruch, Volker Heesen, D. Carbone, Mark J. Bentum, Antonia Rowlinson, Annalisa Bonafede, Rob Fender, J. Sluman, E. Rol, Matthias Steinmetz, Chiara Ferrari, Gijs Molenaar, S. Duscha, G. Kuper, D. D. Mulcahy, Sarod Yatawatta, Philip Best, M. Pietka, H. J. A. Röttgering, Satyendra Thoudam, A. O. Clarke, Adam Stewart, M. P. van Haarlem, Charlotte Sobey, M. Iacobelli, Olaf Wucknitz, Matthias Hoeft, Emanuela Orrú, M. Loose, Ph. Zarka, Adam Deller, Martin J. Hardcastle, Tim D. Staley, Ashish Asgekar, J. Moldon, Dominik J. Schwarz, A. J. van der Horst, Christian Vocks, Rene P. Breton, John Conway, Stephane Corbel, R. C. Vermeulen, Stefan J. Wijnholds, S. van Velzen, T. L. Grobler, Oleg Smirnov, Astronomy, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], University of Southampton, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], School of Physics and Astronomy [Southampton], Netherlands Institute for Radio Astronomy (ASTRON), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Oxford Astrophysics, University of Oxford [Oxford], Rhodes University, Grahamstown, CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Jacobs University [Bremen], 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)-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), Universität Hamburg (UHH), Thüringer Landessternwarte Tautenburg (TLS), Radboud university [Nijmegen], Département de Géologie, Université de Montréal [Montréal], 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), University of Hertfordshire [Hatfield] (UH), Max-Planck-Institut für Radioastronomie (MPIFR), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Curtin University [Perth], Planning and Transport Research Centre (PATREC), 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), Victoria University of Wellington, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], SKA South Africa, Ska South Africa, Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Department of Mathematics, The George Washington University, Washington State University (WSU), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Anton Pannekoek Institute for Astronomy, Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), 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), Institute for Mathematics Applied to Geoscience, National Center for Atmospheric Research [Boulder] (NCAR), SRON Netherlands Institute for Space Research (SRON), 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, Leibniz-Institut für Astrophysik Potsdam (AIP), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Onsala Space Observatory, Dept. of Radio and Space Science, Chalmers University of Technology, Chalmers University of Technology [Göteborg], Ruhr-Universität Bochum [Bochum], University of Oulu, The Netherlands Institute for Radio Astronomy (ASTRON), 7990-AA Dwingeloo, Netherlands, Departament d'Astronomia i Meteorologia [Barcelona], Institut de Ciènces del Cosmos (ICC), Universitat de Barcelona (UB)-Universitat de Barcelona (UB), Center for Information Technology CIT, Université de Groningen, Interactions Son Musique Mouvement, Sciences et Technologies de la Musique et du Son (STMS), 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), Rhodes University, Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), Finca El Encin, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, High Energy Astrophys. & Astropart. Phys (API, FNWI), 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), Université de Montréal (UdeM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), 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), Department of Mathematics [George Washington University] (GW), The George Washington University (GW), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, 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), Universitat de Barcelona (UB), 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), University of Oxford, 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 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), Radboud University [Nijmegen], 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), Universiteit Leiden, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Harvard University-Smithsonian Institution, Stewart, A.J., Fender, R.P., Broderick, J.W., Hassall, T.E., Muñoz-Darias, T., Rowlinson, A., Swinbank, J.D., Staley, T.D., Molenaar, G.J., Scheers, B., Grobler, T.L., Pietka, M., Heald, G., McKean, J.P., Bell, M.E., Bonafede, A., Breton, R.P., Carbone, D., Cendes, Y., Clarke, A.O., Corbel, S., De Gasperin, F., Eislöffel, J., Falcke, H., Ferrari, C., Grießmeier, J.-M., Hardcastle, M.J., Heesen, V., Hessels, J.W.T., Horneffer, A., Iacobelli, M., Jonker, P., Karastergiou, A., Kokotanekov, G., Kondratiev, V.I., Kuniyoshi, M., Law, C.J., van Leeuwen, J., Markoff, S., Miller-Jones, J.C.A., Mulcahy, D., Orru, E., Pandey-Pommier, M., Pratley, L., Rol, E., Röttgering, H.J.A., Scaife, A.M.M., Shulevski, A., Sobey, C.A., Stappers, B.W., Tasse, C., van der Horst, A.J., van Velzen, S., van Weeren, R.J., Wijers, R.A.M.J., Wijnands, R., Wise, M., Zarka, P., Alexov, A., Anderson, J., Asgekar, A., Avruch, I.M., Bentum, M.J., Bernardi, G., Best, P., Breitling, F., Brüggen, M., Butcher, H.R., Ciardi, B., Conway, J.E., Corstanje, A., de Geus, E., Deller, A., Duscha, S., Frieswijk, W., Garrett, M.A., Gunst, A.W., Van Haarlem, M.P., Hoeft, M., Hörandel, J., Juette, E., Kuper, G., Loose, M., Maat, P., McFadden, R., McKay-Bukowski, D., Moldon, J., Munk, H., Norden, M.J., Paas, H., Polatidis, A.G., Schwarz, D., Sluman, J., Smirnov, O., Steinmetz, M., Thoudam, S., Toribio, M.C., Vermeulen, R., Vocks, C., Wijnholds, S.J., Wucknitz, O., Yatawatta, S., ITA, GBR, FRA, DEU, and NLD
Subjects: Astronomy, media_common.quotation_subject, interferometers [instrumentation], radio continuum: general, FOS: Physical sciences, techniques: image processing, 02 engineering and technology, Astrophysics, Low frequency, 01 natural sciences, Instrumentation: interferometer, Celestial pole, 0103 physical sciences, IR-102656, 0202 electrical engineering, electronic engineering, information engineering, instrumentation: interferometers, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common, EWI-27481, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, image processing [techniques], METIS-320906, 020206 networking & telecommunications, Astronomy and Astrophysics, LOFAR, Limiting, Astronomy and Astrophysic, instrumentation: interferometers – techniques: image processing – radio continuum: general, radio, continuum: general, Observation duration, Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, general [radio continuum], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The data were recorded between 2011 December and 2012 April and comprised 2149 11-minute snapshots, each covering 175 deg^2. We have found one convincing candidate astrophysical transient, with a duration of a few minutes and a flux density at 60 MHz of 15-25 Jy. The transient does not repeat and has no obvious optical or high-energy counterpart, as a result of which its nature is unclear. The detection of this event implies a transient rate at 60 MHz of 3.9 (+14.7, -3.7) x 10^-4 day^-1 deg^-2, and a transient surface density of 1.5 x 10^-5 deg^-2, at a 7.9-Jy limiting flux density and ~10-minute time-scale. The campaign data were also searched for transients at a range of other time-scales, from 0.5 to 297 min, which allowed us to place a range of limits on transient rates at 60 MHz as a function of observation duration., 23 pages, 16 figures, 5 tables, accepted for publication in MNRAS
Published: 2016

41. Multiphase signatures of active galactic nucleus feedback in Abell 2597

Author: Alice C. Quillen, Rupal Mittal, G. M. Voit, Helen Russell, Francoise Combes, Joel N. Bregman, Christopher P. O'Dea, Jeremy S. Sanders, Megan Donahue, A. C. Fabian, P. Salomé, Craig L. Sarazin, Michael W. Wise, R. J. Wilman, Stefi A. Baum, Tracy E. Clarke, Grant R. Tremblay, Brian R. McNamara, Gary J. Ferland, J. B. R. Oonk, and Alastair C. Edge
Subjects: Physics, Active galactic nucleus, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Galaxy, Peculiar galaxy, Abell 2744, Space and Planetary Science, Intracluster medium, 0103 physical sciences, Brightest cluster galaxy, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy cluster
Abstract: We present new Chandra X-ray observations of the brightest cluster galaxy (BCG) in the cool-core cluster Abell 2597 (z= 0.0821). The data reveal an extensive kpc-scale X-ray cavity network as well as a 15-kpc filament of soft-excess gas exhibiting strong spatial correlation with archival Very Large Array radio data. In addition to several possible scenarios, multiwavelength evidence may suggest that the filament is associated with multiphase (103-107 K) gas that has been entrained and dredged-up by the propagating radio source. Stemming from a full spectral analysis, we also present profiles and 2D spectral maps of modelled X-ray temperature, entropy, pressure and metal abundance. The maps reveal an arc of hot gas which in projection borders the inner edge of a large X-ray cavity. Although limited by strong caveats, we suggest that the hot arc may be (a) due to a compressed rim of cold gas pushed outwards by the radio bubble or (b) morphologically and energetically consistent with cavity-driven active galactic nucleus heating models invoked to quench cooling flows, in which the enthalpy of a buoyant X-ray cavity is locally thermalized as ambient gas rushes to refill its wake. If confirmed, this would be the first observational evidence for this model.
Published: 2012

42. Residual cooling and persistent star formation amid active galactic nucleus feedback in Abell 2597

Author: Francoise Combes, Rupal Mittal, R. J. Wilman, Stefi A. Baum, J. B. R. Oonk, Michael W. Wise, Grant R. Tremblay, G. M. Voit, Craig L. Sarazin, Brian R. McNamara, Gary J. Ferland, A. C. Fabian, Alastair C. Edge, Helen Russell, Megan Donahue, Christopher P. O'Dea, Joel N. Bregman, Alice C. Quillen, Tracy E. Clarke, P. Salomé, and Jeremy S. Sanders
Subjects: Physics, Active galactic nucleus, 010308 nuclear & particles physics, Star formation, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Cooling flow, 01 natural sciences, Galaxy, Abell 2744, Space and Planetary Science, Intracluster medium, 0103 physical sciences, Elliptical galaxy, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy cluster
Abstract: New Chandra X-ray and Herschel Far-Infrared (FIR) observations enable a multiwavelength study of active galactic nucleus (AGN) heating and intracluster medium (ICM) cooling in the brightest cluster galaxy (BCG) of Abell 2597 (z= 0.0821). The new Chandra observations reveal the central ≲30 kpc X-ray cavity network to be more extensive than previously thought, and associated with enough enthalpy to theoretically inhibit the inferred classical cooling flow. Nevertheless, we present new evidence, consistent with previous results, that a moderately strong residual cooling flow is persisting at 4-8 per cent of the classically predicted rates in a spatially structured manner amid the feedback-driven excavation of the X-ray cavity network. New Herschel observations are used to estimate warm and cold dust masses, a lower limit gas-to-dust ratio and a star formation rate consistent with previous measurements. [O i] and CO(2−1) line profiles are used to constrain the kinematics of the ∼109 M⊙ reservoir of cold molecular gas. The cooling time profile of the ambient X-ray atmosphere is used to map the locations of the observational star formation entropy threshold as well as the theoretical thermal instability threshold. Both lie just outside the ≲30-kpc central region permeated by X-ray cavities, and star formation as well as ionized and molecular gas lie interior to both. The young stars are distributed in an elongated region that is aligned with the radio lobes, and their estimated ages are both younger and older than the X-ray cavity network, suggesting both jet-triggered as well as persistent star formation over the current AGN feedback episode. Bright X-ray knots that are coincident with extended Lyα and far-ultraviolet continuum filaments motivate a discussion of structured cooling from the ambient hot atmosphere along a projected axis that is perpendicular to X-ray cavity and radio axis. We conclude that the cooling ICM is the dominant contributor of the cold gas reservoir fuelling star formation and AGN activity in the Abell 2597 BCG.
Published: 2012

43. Optimized trigger for ultra-high-energy cosmic-ray and neutrino observations with the low frequency radio array

Author: Y. Tang, Harvey Butcher, M. Drost, J. W. Romein, M. Pandey-Pommier, J. Morawietz, A. Renting, A. de Jong, J. Eisloeffel, M. A. Garrett, A. Doorduin, S. Yattawatta, Maaijke Mevius, Rebecca McFadden, K. Dijkstra, A. G. Polatidis, J. Sluman, W. A. van Cappellen, A. van Duin, Jean-Mathias Grießmeier, M. P. van Haarlem, Roberto Pizzo, H. Weggemans, Ben Stappers, Stijn Buitink, P. Maat, M. Loose, M. J. Norden, W. Reich, P. Bennema, C. Broekema, R. Nijboer, E. van der Wal, J. D. Mol, H.-J. Stiepel, H. A. Holties, L.A. Horneffer, H. Meulman, Rene C. Vermeulen, Olaf Wucknitz, J. van Leeuwen, R. H. van de Brink, P. Donker, P. Gruppen, Martin Bell, K. Stuurwold, Joel N. Bregman, G. Bernadi, E. Kooistra, H. Munk, T. Grit, G. Kuper, J. E. Noordam, J.-P. de Reijer, W. N. Brouw, Luitje Koopmans, M. Avruch, G. van Diepen, Heino Falcke, M. de Vos, Mark J. Bentum, B. Ciardi, C. Mallary, Matthias Hoeft, P. Riemers, Michel Tagger, K. Singh, S. ter Veen, A. W. Gunst, H. Paas, J. Roosjen, Ashish Asgekar, M. Ruiter, C. Vogt, Philip Best, M. Gerbers, Michel Arts, P. Lambropoulos, J. E. van Zwieten, Lambert J.M. Nieuwenhuis, E. Mulder, A. Huijgen, G. Schoonderbeek, D. Kant, S. Damstra, C. W. James, M. Brueggen, Albert-Jan Boonstra, A. P. Schoenmakers, A. H. W. M. Coolen, M. Steinmetz, R. J. Dettmar, Stefan J. Wijnholds, Y. Koopman, Olaf Scholten, Oleg Smirnov, R. Overeem, Michael W. Wise, Jörg R. Hörandel, J. M. Anderson, H. Roettgering, A. van Ardenne, Vishambhar Pandey, High Energy Astrophys. & Astropart. Phys (API, FNWI), Netherlands Institute for Radio Astronomy (ASTRON), University of Groningen [Groningen], Max-Planck-Institut für Radioastronomie (MPIFR), University of Southampton, University of Edinburgh, Kapteyn Astronomical Institute [Groningen], Radboud University [Nijmegen], Research School of Astronomy and Astrophysics [Canberra] (RSAA), Australian National University (ANU), Department of Reproduction and Development, Erasmus University Rotterdam, Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, London Institute for Mathematical Sciences, Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], Leiden Observatory [Leiden], Universiteit 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)-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), Thüringer Landessternwarte Tautenburg (TLS), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), DLR Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt [Köln] (DLR), 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), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), University of Reading (UOR), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], 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), KVI - Center for Advanced Radiation Technology, Astronomy, and Kapteyn Astronomical Institute
Subjects: FLUX, Nuclear and High Energy Physics, Lunar radio detection, TELESCOPE, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, UHE NEUTRINOS, 01 natural sciences, 7. Clean energy, law.invention, Radio telescope, Telescope, LIMITS, Frequency filter detection, law, SEARCH, 0103 physical sciences, Ultra-high-energy cosmic ray, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), DETECTOR, 010303 astronomy & astrophysics, Instrumentation, Ultra-high energy neutrinos, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, SPECTRUM, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Detector, Astrophysics::Instrumentation and Methods for Astrophysics, LOFAR, Ultra-high energy cosmic rays, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Neutrino, Nano-second pulse detection, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, EMISSION, Energy (signal processing)
Abstract: When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency pulse is emitted. We plan to use the LOFAR radio telescope to detect these pulses. In this work we propose an efficient trigger implementation for LOFAR optimized for the observation of short radio pulses., Comment: Submitted to Nuclear Instruments and Methods in Physics Research Section A
Published: 2012

44. Orbital and superorbital variability of LS I +61 303 at low radio frequencies with GMRT and LOFAR

Author: Jochen Eislöffel, Heino Falcke, M. Pietka, D. Carbone, Jean-Mathias Grießmeier, Ph. Zarka, A. J. van der Horst, J. van Leeuwen, Adam Stewart, Rene P. Breton, Sera Markoff, Michael W. Wise, John D. Swinbank, Stephane Corbel, Marc Ribó, M. Kuniyoshi, Martin Bell, Ralph A. M. J. Wijers, Guy G. Pooley, J. W. Broderick, Benito Marcote, Rob Fender, C. H. Ishwara-Chandra, M. Serylak, J. M. Paredes, Antonia Rowlinson, Universitat de Barcelona, Departament d'Astronomia i Meteorologia [Barcelona] (DAM), Universitat de Barcelona (UB), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute of Fundamental Research [Bombay] (TIFR), Department of Astrophysical Sciences [Princeton], Princeton University, Oxford Astrophysics, University of Oxford [Oxford], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Mullard Radio Astronomy Observatory (MRAO), University of Cambridge [UK] (CAM), University of Southampton, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], 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)-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), Thüringer Landessternwarte Tautenburg (TLS), 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), 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), Max-Planck-Institut für Radioastronomie (MPIFR), Netherlands Institute for Radio Astronomy (ASTRON), 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), NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911Spanish Ministerio de Econom´ıa y Competitividad (MINECO) under grants AYA2013-47447-C3-1-P, FPA2013-48381-C6-6-P, MDM-2014-0369 of ICCUB (Unidad de Excelencia ‘Mar´ıa de Maeztu’), and the Catalan DEC grant 2014 SGR 86., ANR-11-IDEX-0005-02/10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2011), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), European Project: 332393,EC:FP7:PEOPLE,FP7-PEOPLE-2012-IIF,FAST TRANSIENTS(2014), Tata Institute for Fundamental Research (TIFR), University of Oxford, 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 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), Radboud University [Nijmegen], 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 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), High Energy Astrophys. & Astropart. Phys (API, FNWI), 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: Astrofísica, 010504 meteorology & atmospheric sciences, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], media_common.quotation_subject, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Binary number, Estels binaris, Astrophysics, 01 natural sciences, Raigs gamma, Double stars, 0103 physical sciences, Absorption (electromagnetic radiation), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma rays, Astronomy and Astrophysics, LOFAR, radiation mechanisms: non-thermal – binaries: close – stars: individual: LS I + 61 303 – gamma-rays: stars – radio continuum: stars, Space and Planetary Science, Sky, Modulation, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Radio frequency, Maxima, Astrophysics - High Energy Astrophysical Phenomena
Abstract: LS I +61 303 is a gamma-ray binary that exhibits an outburst at GHz frequencies each orbital cycle of $\approx$ 26.5 d and a superorbital modulation with a period of $\approx$ 4.6 yr. We have performed a detailed study of the low-frequency radio emission of LS I +61 303 by analysing all the archival GMRT data at 150, 235 and 610 MHz, and conducting regular LOFAR observations within the Radio Sky Monitor (RSM) at 150 MHz. We have detected the source for the first time at 150 MHz, which is also the first detection of a gamma-ray binary at such a low frequency. We have obtained the light-curves of the source at 150, 235 and 610 MHz, all of them showing orbital modulation. The light-curves at 235 and 610 MHz also show the existence of superorbital variability. A comparison with contemporaneous 15-GHz data shows remarkable differences with these light-curves. At 15 GHz we see clear outbursts, whereas at low frequencies we see variability with wide maxima. The light-curve at 235 MHz seems to be anticorrelated with the one at 610 MHz, implying a shift of $\sim$ 0.5 orbital phases in the maxima. We model the shifts between the maxima at different frequencies as due to changes in the physical parameters of the emitting region assuming either free-free absorption or synchrotron self-absorption, obtaining expansion velocities for this region close to the stellar wind velocity with both mechanisms., 12 pages, 10 figures, accepted for publication in MNRAS
Published: 2015

45. An automated archival Very Large Array transients survey

Author: Jason W. T. Hessels, John D. Swinbank, Rob Fender, Ben Stappers, Bart Scheers, Martin Bell, H. Spreeuw, Michael W. Wise, James Miller-Jones, Casey J. Law, J. Masters, and Ralph A. M. J. Wijers
Subjects: Very large array, Physics, education.field_of_study, Point source, Pipeline (computing), Population, Astronomy and Astrophysics, Astrophysics, LOFAR, Space and Planetary Science, Limit (music), Snapshot (computer storage), Transient (oscillation), education
Abstract: In this paper we present the results of a survey for radio transients using data obtained from the Very Large Array archive. We have reduced, using a pipeline procedure, 5037 observations of the most common pointings - i.e. the calibrator fields. These fields typically contain a relatively bright point source and are used to calibrate `target' observations: they are therefore rarely imaged themselves. The observations used span a time range ~ 1984 - 2008 and consist of eight different pointings, three different frequencies (8.4, 4.8 and 1.4 GHz) and have a total observing time of 435 hours. We have searched for transient and variable radio sources within these observations using components from the prototype LOFAR transient detection system. In this paper we present the methodology for reducing large volumes of Very Large Array data; and we also present a brief overview of the prototype LOFAR transient detection algorithms. No radio transients were detected in this survey, therefore we place an upper limit on the snapshot rate of GHz frequency transients > 8.0 mJy to rho less than or equal to 0.032 deg^-2 that have typical timescales 4.3 to 45.3 days. We compare and contrast our upper limit with the snapshot rates - derived from either detections or non-detections of transient and variable radio sources - reported in the literature. When compared with the current Log N - Log S distribution formed from previous surveys, we show that our upper limit is consistent with the observed population. Current and future radio transient surveys will hopefully further constrain these statistics, and potentially discover dominant transient source populations. In this paper we also briefly explore the current transient commissioning observations with LOFAR, and the impact they will make on the field.
Published: 2011

46. DIRECT EVIDENCE FOR OUTFLOW OF METAL-ENRICHED GAS ALONG THE RADIO JETS OF HYDRA A

Author: Myriam Gitti, Brian R. McNamara, Michael W. Wise, Laurence P. David, C. C. Kirkpatrick, Paul Nulsen, K. W. Cavagnolo, C. C. Kirkpatrick, M. Gitti, K. W. Cavagnolo, B. R. McNamara, L. P. David, P. E. J. Nulsen, M. W. Wise, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Direct evidence, Astrophysics::High Energy Astrophysical Phenomena, Metallicity, galaxies: active, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, galaxies: abundance, Intracluster medium, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy cluster, Physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, X-rays: galaxies: clusters, Astrophysics of Galaxies (astro-ph.GA), Outflow, Lernaean Hydra, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Using deep Chandra observations of the Hydra A galaxy cluster, we examine the metallicity structure near the central galaxy and along its powerful radio source. We show that the metallicity of the intracluster medium is enhanced by up to 0.2 dex along the radio jets and lobes compared to the metallicity of the undisturbed gas. The enhancements extend from a radius of 20 kpc from the central galaxy to a distance of ~ 120 kpc. We estimate the total iron mass that has been transported out of the central galaxy to be between 2 x 10^7 M_sun and 7 x 10^7 M_sun which represents 10% - 20% of the iron mass within the central galaxy. The energy required to lift this gas is roughly 1% to 5% of the total energetic output of the AGN. Evidently, Hydra A's powerful radio source is able to redistribute metal-enriched, low entropy gas throughout the core of the galaxy cluster. The short re-enrichment time scale < 10^9 yr implies that the metals lost from the central galaxy will be quickly replenished., 4 pages, 4 figures, accepted for publication in ApJ Letters, includes changes based on comments from referee
Published: 2009

47. AN ENERGETIC AGN OUTBURST POWERED BY A RAPIDLY SPINNING SUPERMASSIVE BLACK HOLE OR AN ACCRETING ULTRAMASSIVE BLACK HOLE

Author: Michael W. Wise, David Rafferty, Farnoud Kazemzadeh, Paul Nulsen, Laura Birzan, Brian R. McNamara, C. C. Kirkpatrick, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Solar mass, Supermassive black hole, Bondi accretion, Star formation, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Cooling flow, 01 natural sciences, Galaxy, Accretion (astrophysics), Black hole, Space and Planetary Science, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Powering the 10^62 erg nuclear outburst in the MS0735.6+7421 cluster central galaxy by accretion implies that its supermassive black hole (SMBH) grew by ~6x10^8 solar masses over the past 100 Myr. We place upper limits on the amount of cold gas and star formation near the nucleus of, Accepted for publication in ApJ. Modifications: adopted slightly higher black hole mass using Lauer's M_SMBH vs L_bulge relation and adjusted related quantities; considered more seriously the consequences of a ultramassive black hole, motivated by new Kormendy & Bender paper published after our submission; other modifications per referee comments by Ruszkowski
Published: 2009

48. Chandra observation of the cluster environment of a WAT radio source in Abell 1446

Author: Michael W. Wise, Craig L. Sarazin, T. E. Clarke, E. M. Douglass, Elizabeth L. Blanton, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Radius, Cooling flow, Galaxy, Redshift, Ram pressure, Space and Planetary Science, Intracluster medium, Astrophysics::Galaxy Astrophysics, Galaxy cluster, Line (formation)
Abstract: Wide-angle tail (WAT) radio sources are often found in the centers of galaxy clusters where intracluster medium (ICM) ram pressure may bend the lobes into their characteristic C-shape. We examine the low redshift (z=0.1035) cluster Abell 1446, host to the WAT radio source 1159+583. The cluster exhibits possible evidence for a small-scale cluster-subcluster merger as a cause of the WAT radio source morphology. This evidence includes the presence of temperature and pressure substructure along the line that bisects the WAT as well as a possible wake of stripped interstellar material or a disrupted cool core to the southeast of the host galaxy. A filament to the north may represent cool, infalling gas that's contributing to the WAT bending while spectroscopically determined redshifts of member galaxies may indicate some component of a merger occurring along the line-of-sight. The WAT model of high flow velocity and low lobe density is examined as another scenario for the bending of 1159+583. It has been argued that such a model would allow the ram pressure due to the galaxy's slow motion through the ICM to shape the WAT source. A temperature profile shows that the cluster is isothermal (kT= 4.0 keV) in a series of annuli reaching a radius of 400 kpc. There is no evidence of an ongoing cooling flow. Temperature, abundance, pressure, density, and mass profiles, as well as two-dimensional maps of temperature and pressure are presented., Comment: 40 AASTeX pages including 15 postscript figures; accepted for publication in ApJ
Published: 2008

49. Radiative efficiency and content of extragalactic radio sources: Toward a universal scaling relation between jet power and radio power

Author: Brian R. McNamara, Paul Nulsen, Laura Birzan, Michael W. Wise, Chris Carilli, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Jet (fluid), 010308 nuclear & particles physics, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Electron, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, Synchrotron, law.invention, Luminosity, Magnetic field, Orders of magnitude (time), Space and Planetary Science, law, Beta (plasma physics), 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present an analysis of the energetics and particle content of the lobes of 24 radio galaxies at the cores of cooling clusters. The radio lobes in these systems have created visible cavities in the surrounding hot, X-ray-emitting gas, which allow direct measurement of the mechanical jet power of radio sources over six decades of radio luminosity, independently of the radio properties themselves. Using these measurements, we examine the ratio between radio power and total jet power (the radiative efficiency). We find that jet (cavity) power increases with radio synchrotron power approximately as P_jet ~ (L_radio)^beta, where 0.35 < beta < 0.70 depending on the bandpass of measurement and state of the source. However, the scatter about these relations caused by variations in radiative efficiency spans more than four orders of magnitude. After accounting for variations in synchrotron break frequency (age), the scatter is reduced by ~ 50%, yielding the most accurate scaling relation available between the lobe bolometric radio power and the jet (cavity) power. We place limits on the magnetic field strengths and particle content of the radio lobes using a variety of X-ray constraints. We find that the lobe magnetic field strengths vary between a few to several tens of microgauss depending on the age and dynamical state of the lobes. If the cavities are maintained in pressure balance with their surroundings and are supported by internal fields and particles in equipartition, the ratio of energy in electrons to heavy particles (k) must vary widely from approximately unity to 4000, consistent with heavy (hadronic) jets., 20 pages, 11 figures. Accepted for publication in ApJ
Published: 2008

50. Cosmological Effects of Powerful AGN Outbursts in Galaxy Clusters: Insights from an XMM-Newton Observation of MS 0735+7421

Author: Paul Nulsen, Michael W. Wise, Myriam Gitti, Brian R. McNamara, High Energy Astrophys. & Astropart. Phys (API, FNWI), M. Gitti, B. R. McNamara, P. E. J. Nulsen, and M. W. Wise
Subjects: Physics, X-Rays: Galaxies: Clusters, Galaxies: Cooling Flow, Metallicity, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Cooling flow, Galaxies: Intergalactic Medium, Galaxy, Luminosity, Cosmology: Miscellaneou, Space and Planetary Science, Emissivity, Cluster (physics), Scaling, Galaxy cluster, galaxies: clusters: individual (MS 0735.7+7421), Astrophysics::Galaxy Astrophysics, Galaxies: Clusters: General
Abstract: We report on the results of an analysis of XMM-Newton observations of MS0735+7421, the galaxy cluster which hosts the most energetic AGN outburst currently known. The previous Chandra image shows twin giant X-ray cavities (~200 kpc diameter) filled with radio emission and surrounded by a weak shock front. XMM data are consistent with these findings. The total energy in cavities and shock (~6 \times 10^{61} erg) is enough to quench the cooling flow and, since most of the energy is deposited outside the cooling region (~100 kpc), to heat the gas within 1 Mpc by ~1/4 keV per particle. The cluster exhibits an upward departure (factor ~2) from the mean L-T relation. The boost in emissivity produced by the ICM compression in the bright shells due to the cavity expansion may contribute to explain the high luminosity and high central gas mass fraction that we measure. The scaled temperature and metallicity profiles are in general agreement with those observed in relaxed clusters. Also, the quantities we measure are consistent with the observed M-T relation. We conclude that violent outbursts such as the one in MS0735+7421 do not cause dramatic instantaneous departures from cluster scaling relations (other than the L-T relation). However, if they are relatively common they may play a role in creating the global cluster properties., Comment: 69 pages, 30 figures, accepted for publication in ApJ Main Journal
Published: 2007

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