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1. Magnetism Science with the Square Kilometre Array

Author

George Heald, Sui Ann Mao, Valentina Vacca, Takuya Akahori, Ancor Damas-Segovia, B. M. Gaensler, Matthias Hoeft, Ivan Agudo, Aritra Basu, Rainer Beck, Mark Birkinshaw, Annalisa Bonafede, Tyler L. Bourke, Andrea Bracco, Ettore Carretti, Luigina Feretti, J. M. Girart, Federica Govoni, James A. Green, JinLin Han, Marijke Haverkorn, Cathy Horellou, Melanie Johnston-Hollitt, Roland Kothes, Tom Landecker, Błażej Nikiel-Wroczyński, Shane P. O’Sullivan, Marco Padovani, Frédérick Poidevin, Luke Pratley, Marco Regis, Christopher John Riseley, Tim Robishaw, Lawrence Rudnick, Charlotte Sobey, Jeroen M. Stil, Xiaohui Sun, Sharanya Sur, A. Russ Taylor, Alec Thomson, Cameron L. Van Eck, Franco Vazza, Jennifer L. West, and the SKA Magnetism Science Working Group

Subjects
magnetic fields, polarization, instrumentation: interferometers, techniques: polarimetric, telescopes, Astronomy, QB1-991
Abstract

The Square Kilometre Array (SKA) will answer fundamental questions about the origin, evolution, properties, and influence of magnetic fields throughout the Universe. Magnetic fields can illuminate and influence phenomena as diverse as star formation, galactic dynamics, fast radio bursts, active galactic nuclei, large-scale structure, and dark matter annihilation. Preparations for the SKA are swiftly continuing worldwide, and the community is making tremendous observational progress in the field of cosmic magnetism using data from a powerful international suite of SKA pathfinder and precursor telescopes. In this contribution, we revisit community plans for magnetism research using the SKA, in light of these recent rapid developments. We focus in particular on the impact that new radio telescope instrumentation is generating, thus advancing our understanding of key SKA magnetism science areas, as well as the new techniques that are required for processing and interpreting the data. We discuss these recent developments in the context of the ultimate scientific goals for the SKA era.

Published
2020
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2. Untangling Cosmic Magnetic Fields: Faraday Tomography at Metre Wavelengths with LOFAR

Author

Shane P. O’Sullivan, Marcus Brüggen, Cameron L. Van Eck, Martin J. Hardcastle, Marijke Haverkorn, Timothy W. Shimwell, Cyril Tasse, Valentina Vacca, Cathy Horellou, and George Heald

Subjects
magnetic fields, Faraday tomography, large-scale structure, AGN, Milky Way, Astronomy, QB1-991
Abstract

The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio-polarisation observations. In particular, observations at metre wavelengths provide significantly better Faraday depth accuracies compared to traditional centimetre-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengths (MHz frequencies). In this work, Faraday tomography is used to characterise the Faraday rotation properties of polarised sources found in data from the LOFAR Two-Metre Sky Survey (LoTSS). Of the 76 extragalactic polarised sources analysed here, we find that all host a radio-loud AGN (Active Galactic Nucleus). The majority of the sources (∼64%) are large FRII radio galaxies with a median projected linear size of 710 kpc and median radio luminosity at 144 MHz of 4 × 10 26 W Hz − 1 (with ∼13% of all sources having a linear size >1 Mpc). In several cases, both hotspots are detected in polarisation at an angular resolution of ∼20″ . One such case allowed a study of intergalactic magnetic fields on scales of 3.4 Mpc. Other detected source types include an FRI radio galaxy and at least eight blazars. Most sources display simple Faraday spectra, but we highlight one blazar that displays a complex Faraday spectrum, with two close peaks in the Faraday dispersion function.

Published
2018
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4. A low-frequency study of linear polarization in radio galaxies

Author

Cathy Horellou, Martin J. Hardcastle, Daniel J. Smith, George Heald, Shane O'Sullivan, Jeremy J. Harwood, and V. H. Mahatma

Subjects
Physics, Line-of-sight, 010308 nuclear & particles physics, Linear polarization, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, LOFAR, Astrophysics, Low frequency, Polarization (waves), Astrophysics - Astrophysics of Galaxies, 01 natural sciences, symbols.namesake, Space and Planetary Science, Angular diameter, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Faraday effect, symbols, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Radio galaxies are linearly polarized -- an important property that allows us to infer the properties of the magnetic field of the source and its environment. However at low frequencies, Faraday rotation substantially depolarizes the emission, meaning that comparatively few polarized radio galaxies are known at low frequencies. Using the LOFAR Two Metre Sky Survey at 150 MHz and at 20 arcsec resolution, we select 342 radio galaxies brighter than 50 mJy and larger than 100 arcsec in angular size, of which 67 are polarized (18 per cent detection fraction). These are predominantly Fanaroff Riley type II (FR-II) sources. The detection fraction increases with total flux density, and exceeds 50 per cent for sources brighter than 1 Jy. We compare the sources in our sample detected by LOFAR to those also detected in NVSS at 1400 MHz, and find that our selection bias toward bright radio galaxies drives a tendency for sources depolarized between 1400 and 150 MHz to have flatter spectra over that frequency range than those that remain polarized at 150 MHz. By comparing observed rotation measures with an analytic model we find that we are preferentially sensitive to sources in low mass environments. We also infer that sources with one polarized hotspot are inclined by a small angle to the line of sight, while sources with hotspots in both lobes lie in the plane of the sky. We conclude that low frequency polarization in radio galaxies is related to a combination of environment, flux density and jet orientation., 20 pages, 19 figures. Accepted for publication in MNRAS, December 22nd 2020

Published
2020

5. The magnetized disk-halo transition region of M 51

Author

M. Kierdorf, Fatemeh Tabatabaei, Andrew Fletcher, S. A. Mao, J. Ott, Cathy Horellou, Rainer Beck, Aritra Basu, and Marijke Haverkorn

Subjects
010504 meteorology & atmospheric sciences, Astronomy, FOS: Physical sciences, Synchrotron radiation, Field strength, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Spiral galaxy, Condensed matter physics, 010308 nuclear & particles physics, Linear polarization, Astronomy and Astrophysics, galaxies: individual: M, Polarization (waves), galaxies: general, Astrophysics - Astrophysics of Galaxies, Galaxy, Magnetic field, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Degree of polarization, Halo, galaxies: magnetic fields, galaxies: ISM
Abstract

The grand-design face-on spiral galaxy M51 is an excellent laboratory for studying magnetic fields in galaxies. We present new observations of M51 using the VLA at the frequency range of S-band (2-4GHz), to shed new light on the transition region between the disk and halo. We present images of the distributions of the total intensity, polarized intensity, degree of polarization, and rotation measure (RM). The RM distribution in S-band shows a fluctuating pattern without any apparent large-scale structure. We discuss a model of the depolarization of synchrotron radiation in a multi-layer magneto-ionic medium and compare the model predictions to the polarization data of M51 between 1-8GHz. Since the model predictions strongly differ within the wavelength range of the S-band, the new data are essential. The parameters of the model are adjusted to fit to the data of polarization fractions in a few selected regions. In three spiral arm regions, the turbulent field in the disk dominates with strengths between 18muG and 24muG, while the regular field strengths are 8-16muG. In one inter-arm region, the regular field strength of 18muG exceeds that of the turbulent field of 11muG. The regular field strengths in the halo are 3-5muG. The observed RMs in the disk-halo transition region are probably dominated by tangled regular fields, as predicted from models of evolving dynamos, and/or vertical fields, as predicted from numerical simulations of Parker instabilities or galactic winds. Both types of magnetic fields have frequent reversals on scales similar to or larger than the beam size (550pc) that contribute to an increase of the RM dispersion and to distortions of any large-scale pattern of the regular field. Our study devises new ways of analyzing and interpreting broadband multi-frequency polarization data that will be applicable to future data from, for example, the Square Kilometre Array., Comment: Accepted for publication in A&A

Published
2020

6. Characterising the Extended Morphologies of BL Lacertae Objects at 144 MHz with LOFAR

Author

Urszula Pajdosz-Śmierciak, Martin J. Hardcastle, Francesco Massaro, Cathy Horellou, Beatriz Mingo, Raffaella Morganti, Alessandro Capetti, Shane O'Sullivan, M. Pandey-Pommier, Huub Röttgering, G. Gürkan, John L. Quinn, Ranieri D. Baldi, S. Mooney, Astronomy, 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), 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), 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), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Active galactic nucleus, Radio galaxy, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Population, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radio source catalogs, radio source catalogs, 01 natural sciences, 158, 1356, 0103 physical sciences, education, 010303 astronomy & astrophysics, media_common, Physics, education.field_of_study, Spectral index, Line-of-sight, 010308 nuclear & particles physics, Computer Science::Information Retrieval, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Sky, BL Lacertae objects, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present a morphological and spectral study of a sample of 99 BL Lac objects using the LOFAR Two-Metre Sky Survey Second Data Release (LDR2). Extended emission has been identified at gigahertz frequencies around BL Lac objects, but with LDR2 it is now possible to systematically study their morphologies at 144 MHz, where more diffuse emission is expected. LDR2 reveals the presence of extended radio structures around 66/99 of the BL Lac nuclei, with angular extents ranging up to 115″, corresponding to spatial extents of 410 kpc. The extended emission is likely to be both unbeamed diffuse emission and beamed emission associated with relativistic bulk motion in jets. The spatial extents and luminosities of the extended emission are consistent with the unification scheme for active galactic nuclei, where BL Lac objects correspond to low-excitation radio galaxies with the jet axis aligned along the line of sight. While extended emission is detected around the majority of BL Lac objects, the median 144–1400 MHz spectral index and core dominance at 144 MHz indicate that the core component contributes ∼42% on average to the total low-frequency flux density. A stronger correlation was found between the 144 MHz core flux density and the γ-ray photon flux (r = 0.69) than between the 144 MHz extended flux density and the γ-ray photon flux (r = 0.42). This suggests that the radio-to-γ-ray connection weakens at low radio frequencies because the population of particles that give rise to the γ-ray flux are distinct from the electrons producing the diffuse synchrotron emission associated with spatially extended features.

Published
2021

7. Active gas features in three HSC-SSP CAMIRA clusters revealed by high angular resolution analysis of MUSTANG-2 SZE and XXL X-ray observations

Author

Vernesa Smolčić, Keiichi Umetsu, Fabio Gastaldello, Keigo Tanaka, Dominique Eckert, Elinor Medezinski, Cathy Horellou, Craig L. Sarazin, Atsushi Yoshida, Sara Stanchfield, Kotaro Kohno, John ZuHone, Tony Mroczkowski, Chong Yang, Brian Mason, Marguerite Pierre, Satoshi Miyazaki, Mark Birkinshaw, Hiroki Akamatsu, Masamune Oguri, Mauro Sereno, Tetsu Kitayama, Jonathan Sievers, Charles Romero, Ayaka Honda, I-Non Chiu, Atsushi J. Nishizawa, Ikuyuki Mitsuishi, Yen-Ting Lin, Florian Pacaud, Kai-Yang Lin, Nobuhiro Okabe, Mark J. Devlin, Simon Dicker, Naomi Ota, Ryoichi Yamamoto, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112))

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), galaxies: clusters: intracluster medium, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, gravitational lensing: weak, Supercluster, weak [gravitational lensing], 0103 physical sciences, Cluster (physics), clusters: general [galaxies], Angular resolution, Surface brightness, 010306 general physics, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, galaxies: clusters: general, radio continuum: galaxies, X-rays: galaxies: clusters, Astrophysics - Cosmology and Nongalactic Astrophysics, Physics, Astronomy and Astrophysics, Galaxy, Redshift, Core (optical fiber), Space and Planetary Science, clusters: intracluster medium [galaxies], galaxies [dio continuum], galaxies: clusters [X-rays], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We present results from simultaneous modeling of high angular resolution GBT/MUSTANG-2 90 GHz Sunyaev-Zel'dovich effect (SZE) measurements and XMM-XXL X-ray images of three rich galaxy clusters selected from the HSC-SSP Survey. The combination of high angular resolution SZE and X-ray imaging enables a spatially resolved multi-component analysis, which is crucial to understand complex distributions of cluster gas properties. The targeted clusters have similar optical richnesses and redshifts, but exhibit different dynamical states in their member galaxy distributions: a single-peaked cluster, a double-peaked cluster, and a cluster belonging to a supercluster. A large-scale residual pattern in both regular Compton-parameter $y$ and X-ray surface brightness distributions is found in the single-peaked cluster, indicating a sloshing mode. The double-peaked cluster shows an X-ray remnant cool core between two SZE peaks associated with galaxy concentrations. The temperatures of the two peaks reach $\sim20-30$ keV in contrast to the cool core component of $\sim2$ keV, indicating a violent merger. The main SZE signal for the supercluster is elongated along a direction perpendicular to the major axis of the X-ray core, suggesting a minor merger before core passage. The $S_X$ and $y$ distributions are thus perturbed at some level, regardless of the optical properties. We find that the integrated Compton $y$ parameter and the temperature for the major merger are boosted from those expected by the weak-lensing mass and those for the other two clusters show no significant deviations, which is consistent with predictions of numerical simulations., Comment: 36 pages, 25 figures, 5 tables; accepted for the publication in MNRAS

Published
2021

8. LOFAR Deep Fields: probing a broader population of polarized radio galaxies in ELAIS-N1

Author

George Heald, C. Tasse, V. Vacca, Błażej Nikiel-Wroczyński, Isabella Prandoni, R.-J. Dettmar, Stephen Bourke, Charlotte Sobey, N. Herrera Ruiz, Martin J. Hardcastle, Vibor Jelić, Marco Iacobelli, J. Sabater, Shane O'Sullivan, S. Piras, R. Kondapally, Krzysztof T. Chyzy, Timothy W. Shimwell, Ettore Carretti, Marcus Brüggen, Philip Best, and Cathy Horellou

Subjects
Radio galaxy, media_common.quotation_subject, Population, Polarimetry, FOS: Physical sciences, Astrophysics, Low frequency, 01 natural sciences, symbols.namesake, 0103 physical sciences, Faraday effect, polarimetric [techniques], education, 010303 astronomy & astrophysics, individual: ELAIS-N1 [galaxies], media_common, Physics, education.field_of_study, polarization, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, galaxies: individual: ELAIS-N1, radio continuum: galaxies, techniques: polarimetric, Polarization (waves), Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), symbols
Abstract

We present deep polarimetric observations of the European Large Area ISO Survey-North 1 (ELAIS-N1) field using the Low Frequency Array (LOFAR) at 114.9-177.4 MHz. The ELAIS-N1 field is part of the LOFAR Two-metre Sky Survey deep fields data release I. For six eight-hour observing epochs, we align the polarization angles and stack the 20"-resolution Stokes $Q$, $U$-parameter data cubes. This produces a 16 deg$^2$ image with 1$\sigma_{\rm QU}$ sensitivity of 26 $\mu$Jy/beam in the central area. In this paper, we demonstrate the feasibility of the stacking technique, and we generate a catalog of polarized sources in ELAIS-N1 and their associated Faraday rotation measures (RMs). While in a single-epoch observation we detect three polarized sources, this number increases by a factor of about three when we consider the stacked data, with a total of ten sources. This yields a surface density of polarized sources of one per 1.6 deg$^2$. The Stokes $I$ images of three of the ten detected polarized sources have morphologies resembling those of FR I radio galaxies. This represents a greater fraction of this type of source than previously found, which suggests that more sensitive observations may help with their detection., Comment: This paper is part of the 1st data release of the LoTSS Deep Fields. Accepted for publication in A&A. 14 pages, 9 figures, 7 tables

Published
2021

9. The XXL Survey. XLIII. The quasar radio loudness dichotomy exposed via radio luminosity functions obtained by combining results from COSMOS and XXL-S X-ray selected quasars

Author

Sarah K. Leslie, J. Delhaize, Stefano Marchesi, Vernesa Smolčić, A. Butler, Jeyhan S. Kartaltepe, Manolis Plionis, Konstantinos Kolokythas, Eleni Vardoulaki, L. Ceraj, Marguerite Pierre, K. Tisanić, Mladen Novak, Cathy Horellou, Ivan Delvecchio, and G. Zamorani

Subjects
PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Loudness, Luminosity, 0103 physical sciences, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, evolution [galaxies], Luminosity function (astronomy), Physics, general [quasars], 010308 nuclear & particles physics, X-ray, Astronomy and Astrophysics, Quasar, Astrophysics - Astrophysics of Galaxies, Redshift, Galaxy, quasars: general, galaxies: active, galaxies: evolution, galaxies: high-redshift, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], high-redshift [galaxies]
Abstract

We studied a sample of 274 radio and X-ray selected quasars (XQSOs) detected in the COSMOS and XXL-S radio surveys at 3 GHz and 2.1 GHz, respectively. This sample was identified by adopting a conservative threshold in X-ray luminosity, Lx [2-10\ keV] >= 10^44 erg/s, selecting only the most powerful quasars. Using available multiwavelength data, we examined various criteria for the selection of radio-loud (RL) and radio-quiet (RQ) XQSOs, finding that the number of RL/RQ XQSOs changes significantly depending on the chosen criterion. This discrepancy arises due to the different criteria tracing different physical processes and due to our sample being selected from flux-limited radio and X-ray surveys. Another approach to study the origin of radio emission in XQSOs is via their radio luminosity function (RLF). We constructed the XQSO 1.4 GHz radio luminosity functions (RLFs) in six redshift bins at 0.5, 14 pages, 11 figures

Published
2020

10. XXL-HSC: An updated catalogue of high-redshift (z ≥ 3.5) X-ray AGN in the XMM-XXL northern field

Author

C. Vignali, S. Paltani, I. Georgantopoulos, Yoshiki Toba, E. Pouliasis, Yoshihiro Ueda, Tohru Nagao, L. Chiappetti, Roberto Gilli, C. Garrel, Marguerite Pierre, Cathy Horellou, Elias Koulouridis, Ángel Ruiz, and Masayuki Akiyama

Subjects
Physics, Field (physics), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, Redshift
Abstract

X-rays offer a reliable method to identify Active Galactic Nuclei (AGN). However, in the high-redshift Universe X-ray AGN are poorly sampled due to their relatively low space density and the small areas covered by X-ray surveys. In addition to wide-area X-ray surveys, it is important to have deep optical data in order to locate the optical counterparts and determine their redshifts. In this work, we build a high-redshift ($z\geqslant3.5$) X-ray selected AGN sample in the XMM-XXL northern field using the most updated [0.5-2 keV] catalogue along with a plethora of new spectroscopic and multi-wavelength catalogues, including the deep optical Subaru Hyper Suprime-Cam (HSC) data reaching magnitude limits i$\sim$26 mag. We select all the spectroscopically confirmed AGN and complement this sample with high-redshift candidates that are HSC g- and r-band dropouts. To confirm the dropouts, we derive their photometric redshifts using spectral energy distribution techniques. We end up with a sample of 54 high-z sources (28 with spec-z), the largest in this field so far (almost three times larger than in previous studies), and we estimate the possible contamination and completeness. We calculate the number counts (logN-logS) in different redshift bins and compare our results with previous studies and models. We provide the strongest high-redshift AGN constraints yet at bright fluxes ($\rm f_{0.5-2~keV} > 10^{-15} erg~s^{-1}~cm^{-2}$). The samples of $z\geqslant3.5$, $z\geqslant4$ and $z\geqslant5$ are in agreement with an exponential decline model similar to that witnessed at optical wavelengths. Our work emphasizes the importance of using wide area X-ray surveys with deep optical data to uncover high redshift AGN., Accepted for publication in A&A. 16 pages, 12 figures, 3 tables

Published
2022

11. The XXL Survey

Author

Konstantinos Kolokythas, M. N. Bremer, K. Tisanić, Mark Birkinshaw, Cathy Horellou, Bruno Šlaus, H. J. A. Röttgering, Paolo Ciliegi, L. Ceraj, Mladen Novak, M. Huynh, Sotiria Fotopoulou, L. Chiappetti, Marguerite Pierre, Somak Raychaudhury, Hubertus Intema, Vernesa Smolčić, N. Jurlin, University of Zagreb, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Durham University, University of Geneva [Switzerland], INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Netherlands Institute for Radio Astronomy (ASTRON), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], University of Bristol [Bristol], INAF - Osservatorio Astronomico di Milano (OAM), Chalmers University of Technology [Göteborg], CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), 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), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], North-West University [South Aftrica] (NWU), 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 de Paris (UP), Inter-University Centre for Astronomy and Astrophysics [Pune] (IUCAA), The Saclay group acknowledges long-term support from the Centre National d’Etudes Spatiales (CNES)., XXL is an international project based around an XMM Very Large Programme., European Project: 337595,EC:FP7:ERC,ERC-2013-StG,COSMASS(2014), Astronomy, Université de Genève = University of Geneva (UNIGE), Universiteit Leiden, and 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)

Subjects
Active galactic nucleus, PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, Likelihood ratio method, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, nuclei [galaxies], galaxies: nuclei, radio continuum: galaxies, accretion, accretion disks, galaxies: evolution, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, Source counts, 010303 astronomy & astrophysics, Density evolution, evolution [galaxies], Astrophysics::Galaxy Astrophysics, Physics, Giant Metrewave Radio Telescope, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Redshift, Accretion (astrophysics), galaxies [radio continuum], Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We study the space density evolution of active galactic nuclei (AGN) using the 610 MHz radio survey of the XXL-North field, performed with the Giant Metrewave Radio Telescope. The survey covers an area of 30.4 deg2, with a beamsize of 6.5 arcsec. The survey is divided into two parts, one covering an area of 11.9 deg2 with 1σ rms noise of 200 μJy beam−1 and the other spanning 18.5 deg2 with rms noise of 45 μJy beam−1. We extracted the catalog of radio components above 7σ. The catalog was cross-matched with a multi-wavelength catalog of the XXL-North field (covering about 80% of the radio XXL-North field) using a likelihood ratio method, which determines the counterparts based on their positions and their optical properties. The multi-component sources were matched visually with the aid of a computer code: Multi-Catalog Visual Cross-Matching. A flux density cut above 1 mJy selects AGN hosts with a high purity in terms of star formation contamination based on the available source counts. After cross-matching and elimination of observational biases arising from survey incompletenesses, the number of remaining sources was 1150. We constructed the rest-frame 1.4 GHz radio luminosity functions of these sources using the maximum volume method. This survey allows us to probe luminosities of 23 ≲ log(L1.4 GHz[W Hz−1]) ≲ 28 up to redshifts of z ≈ 2.1. Our results are consistent with the results from the literature in which AGN are comprised of two differently evolving populations, where the high luminosity end of the luminosity functions evolves more strongly than the low-luminosity end.

Published
2020

12. The LOFAR view of intergalactic magnetic fields with giant radio galaxies

Author

Cathy Horellou, Shane O'Sullivan, George Heald, Ettore Carretti, Pratik Dabhade, Marco Iacobelli, Annalisa Bonafede, C. Stuardi, V. Vacca, R. Morganti, Marcus Brüggen, Astronomy, Stuardi C., O'Sullivan S.P., Bonafede A., Bruggen M., Dabhade P., Horellou C., Morganti R., Carretti E., Heald G., Iacobelli M., and Vacca V.

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Radio galaxy, astro-ph.GA, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, magnetic fields, 01 natural sciences, law.invention, symbols.namesake, law, 0103 physical sciences, Faraday effect, Faraday cage, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Physics, NRAO VLA Sky Survey, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Galaxy, techniques: polarimetric, Magnetic field, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.CO, symbols, Intergalactic travel, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Giant radio galaxies (GRGs) are physically large radio sources that extend well beyond their host galaxy environment. Their polarization properties are affected by the poorly constrained magnetic field that permeates the intergalactic medium on Mpc scales. A low frequency ($, Comment: 25 pages, 9 figures, 3 tables, accepted by A&A

Published
2020

13. New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations

Author

C. Stuardi, Huub Röttgering, Timothy W. Shimwell, Martin J. Hardcastle, Marcus Brüggen, Cathy Horellou, Nicola Locatelli, V. Vacca, Shane O'Sullivan, Franco Vazza, George Heald, C. Tasse, Ettore Carretti, Tessa Vernstrom, 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), O’Sullivan, S P, Brüggen, M, Vazza, F, Carretti, E, Locatelli, N T, Stuardi, C, Vacca, V, Vernstrom, T, Heald, G, Horellou, C, Shimwell, T W, Hardcastle, M J, Tasse, C, Röttgering, H, and PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, magnetic field, Astrophysics::Cosmology and Extragalactic Astrophysics, magnetization, 01 natural sciences, rotation, techniques: polarimetric -galaxies:active, symbols.namesake, Magnetization, Cosmic web, 0103 physical sciences, Faraday effect, Astrophysics - Cosmology and Nongalactic Astrophysic, structure, AGN, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, radio continuum: galaxies, 010308 nuclear & particles physics, galaxy: radio wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Automatic Keywords, techniques: polarimetric, field strength, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, galaxy: cluster, galaxies: magnetic field, large-scale structure of Universe, radio continuum: galaxie, galaxies: magnetic fields, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Measuring the properties of extragalactic magnetic fields through the effect of Faraday rotation provides a means to understand the origin and evolution of cosmic magnetism. Here we use data from the LOFAR Two-Metre Sky Survey (LoTSS) to calculate the Faraday rotation measure (RM) of close pairs of extragalactic radio sources. By considering the RM difference ($\Delta$RM) between physical pairs (e.g. double-lobed radio galaxies) and non-physical pairs (i.e. close projected sources on the sky), we statistically isolate the contribution of extragalactic magnetic fields to $\Delta$RM along the line of sight between non-physical pairs. From our analysis, we find no significant difference between the $\Delta$RM distributions of the physical and non-physical pairs, limiting the excess Faraday rotation contribution to $< 1.9$ rad/m$^2$ ($\sim$$95\%$ confidence). We use this limit with a simple model of an inhomogeneous universe to place an upper limit of 4 nG on the cosmological co-moving magnetic field strength on Mpc scales. We also compare the RM data with a more realistic suite of cosmological MHD simulations, that explore different magnetogenesis scenarios. Both magnetization of the large scale structure by astrophysical processes such as galactic and AGN outflows, and simple primordial scenarios with seed magnetic field strengths $< 0.5$ nG cannot be rejected by the current data; while stronger primordial fields or models with dynamo amplification in filaments are disfavoured., Comment: 13 pages, 8 figures, 2 tables. Accepted to MNRAS. Full version of Table 2 available at https://www.dropbox.com/s/axqrl8sbmj1f2c1/RMpairs_Table_2.dat?dl=0

Published
2020
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14. The XXL Survey

Author

G. Lagache, Alessandro Monfardini, R. Adam, Pascale Andre, A. Cappi, Bruno Altieri, M. Sanchez Portal, G. Pisano, A. Bideaud, Shibo Shu, Florian Kéruzoré, D. Boutigny, Simon Doyle, K. F. Schuster, V. Revéret, Marguerite Pierre, Alicia Gomez, A. Beelen, Sotiria Fotopoulou, Keiichi Umetsu, J. Goupy, Albrecht Sievers, C. Tucker, M. Ricci, C. Romero, Florian Ruppin, Adam Mantz, H. Aussel, F. Gastaldello, P. D. Mauskopf, O. Bourrion, Mark Birkinshaw, C. Kramer, A. Andrianasolo, Mauro Sereno, L. Perotto, A. Catalano, C. Ferrari, C. Benoist, D. Eckert, L. Faccioli, L. Chiappetti, Florian Pacaud, P. A. R. Ade, F.-X. Désert, Oliver Hahn, Alain Benoit, N. Ponthieu, Emanuela Pompei, Manuel Calvo, Cathy Horellou, Elias Koulouridis, E. F. C. Driessen, A. Ritacco, M. De Petris, J. F. Macías-Pérez, S. Maurogordato, Bilal Ladjelate, S. Leclercq, S. Berta, Paul Giles, Ben J Maughan, J.-F. Lestrade, Malcolm N. Bremer, H. Roussel, Umetsu, K. [0000-0002-7196-4822], Koulouridis, E. [0000-0002-9423-3723], Altieri, B. [0000-0003-3936-0284], Giles, P. [0000-0003-4937-8453], Ricci, M. [0000-0002-3645-9652], European Research Council (ERC), Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Agenzia Spaziale Italiana (ASI), European Commission (EC), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), 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)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble [2020-....] (OSUG [2020-....]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....]), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology [2020-....] (Grenoble INP [2020-....]), Université Grenoble Alpes [2020-....] (UGA [2020-....])-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Centre National de la Recherche Scientifique (CNRS), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2020-....] (Grenoble INP [2020-....]), Université Grenoble Alpes [2020-....] (UGA [2020-....]), Instituto de RadioAstronomía Milimétrica (IRAM), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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 National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Herschel Science Centre, European Space Agency (ESA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Sud - Paris 11 (UP11), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Hélium : du fondamental aux applications (HELFA), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Astronomy Instrumentation [Cardiff], School of Physics and Astronomy [Cardiff], Cardiff University-Cardiff University, University of Bristol [Bristol], Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Cryogénie (Cryo), INAF - Osservatorio Astronomico di Capodimonte (OAC), Istituto Nazionale di Astrofisica (INAF), University of Geneva [Switzerland], Durham University, Centre de Recherches sur les Littératures et la Sociopoétique (CELIS), Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Observatoire de Paris - Site de Paris (OP), 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), Utah State University (USU), IRCAV - Institut de Recherche sur le Cinéma et l'Audiovisuel - EA 185 (IRCAV), Université Sorbonne Nouvelle - Paris 3-LABEX ICCA, Université Paris 13 (UP13)-Université Sorbonne Nouvelle - Paris 3-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC)-Université Sorbonne Paris Nord-Université Paris 13 (UP13)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC)-Université Sorbonne Paris Nord, European Southern Observatory (ESO), Astrophysique, Laboratoire de physique de l'ENS - ENS Paris (LPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Herschel Science Center [Madrid], European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Université de Genève = University of Geneva (UNIGE), Cardiff University, 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), Agence Spatiale Européenne = European Space Agency (ESA), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Hélium : du fondamental aux applications (NEEL - HELFA), Cryogénie (NEEL - Cryo), INAF - Osservatorio Astronomico di Milano (OAM), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Université Côte d'Azur (UCA), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Chalmers University of Technology [Gothenburg, Sweden], Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Universitätsklinikum Bonn (UKB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), INAF - Osservatorio Astronomico di Bologna (OABO), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Academia Sinica, 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Université Paris 13 (UP13)-Université Sorbonne Nouvelle - Paris 3-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Université Sorbonne Paris Nord-Université Paris 13 (UP13)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Université Sorbonne Paris Nord, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2020-....] (Grenoble INP [2020-....]), Laboratoire de Physique Théorique de l'ENS (LPTENS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), galaxies: clusters: intracluster medium, cluster: intracluester medium [Galaxies], high angular resolution / galaxies, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Measure (mathematics), intracluster medium [clusters], 0103 physical sciences, Cluster (physics), clusters, individual, Brightest cluster galaxy, galaxies: clusters: individual: XLSSC 102, 010303 astronomy & astrophysics, Scaling, Galaxy cluster, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Galaxies: clusters: individual: XLSSC 102, Galaxies: clusters: intracluster medium, Techniques: high angular resolution, X-rays: galaxies: clusters, techniques: high angular resolution, Astronomy and Astrophysics, Galaxy, clusters: individual: XLSSC 102 [Galaxies], high angular resolution [Techniques], Space and Planetary Science, XLSSC 102 / galaxies, Substructure, galaxies: clusters [X-rays], techniques, Low Mass, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

High-mass clusters at low redshifts have been intensively studied at various wavelengths. However, while more distant objects at lower masses constitute the bulk population of future surveys, their physical state remain poorly explored to date. In this paper, we present resolved observations of the Sunyaev-Zel'dovich (SZ) effect, obtained with the NIKA2 camera, towards the cluster of galaxies XLSSC 102, a relatively low-mass system (M500 ∼ 2 × 1014 M·) at z = 0.97 detected from the XXL survey. We combine NIKA2 SZ data, XMM-Newton X-ray data, and Megacam optical data to explore, respectively, the spatial distribution of the gas electron pressure, the gas density, and the galaxies themselves. We find significant offsets between the X-ray peak, the SZ peak, the brightest cluster galaxy, and the peak of galaxy density. Additionally, the galaxy distribution and the gas present elongated morphologies. This is interpreted as the sign of a recent major merging event, which induced a local boost of the gas pressure towards the north of XLSSC 102 and stripped the gas out of the galaxy group. The NIKA2 data are also combined with XXL data to construct the thermodynamic profiles of XLSSC 102, obtaining relatively tight constraints up to about ∼r500, and revealing properties that are typical of disturbed systems. We also explore the impact of the cluster centre definition and the implication of local pressure substructure on the recovered profiles. Finally, we derive the global properties of XLSSC 102 and compare them to those of high-mass-and-low-redshift systems, finding no strong evidence for non-standard evolution. We also use scaling relations to obtain alternative mass estimates from our profiles. The variation between these different mass estimates reflects the difficulty to accurately measure the mass of low-mass clusters at z ∼ 1, especially with low signal-to-noise ratio data and for a disturbed system. However, it also highlights the strength of resolved SZ observations alone and in combination with survey-like X-ray data. This is promising for the study of high redshift clusters from the combination of eROSITA and high resolution SZ instruments and will complement the new generation of optical surveys from facilities such as LSST and Euclid., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Published
2020

15. All good things come in threes: the third image of the lensed quasar PKS1830-211

Author

S. Jaswanth, Cathy Horellou, Sebastien Muller, and Ivan Marti-Vidal

Subjects
Physics, Spectral index, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Einstein ring, 010308 nuclear & particles physics, Continuum (design consultancy), Strong gravitational lensing, FOS: Physical sciences, Astronomy and Astrophysics, Quasar, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, symbols.namesake, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, symbols, Millimeter, Angular resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Hubble's law
Abstract

Strong gravitational lensing distorts our view of sources at cosmological distances but brings invaluable constraints on the mass content of foreground objects and on the geometry and properties of the Universe. We report the detection of a third continuum source toward the strongly lensed quasar PKS1830-211 in ALMA multi-frequency observations of high dynamic range and high angular resolution. This third source is point-like and located slightly to the north of the diagonal joining the two main lensed images, A and B, 0.3 arcsec away from image B. It has a flux density that is ~140 times weaker than images A and B and a similar spectral index, compatible with synchrotron emission. We conclude that this source is most likely the expected highly de-magnified third lensed image of the quasar. In addition, we detect, for the first time at millimeter wavelengths, weak and asymmetrical extensions departing from images A and B that correspond to the brightest regions of the Einstein ring seen at centimeter wavelengths. Their spectral index is steeper than that of compact images A, B, and C, which suggests that they arise from a different component of the quasar. Using the GravLens code, we explore the implications of our findings on the lensing model and propose a simple model that accurately reproduces our ALMA data and previous VLA observations. With a more precise and accurate measurement of the time delay between images A and B, the system PKS1830-211 could help to constrain the Hubble constant to a precision of a few percent., Comment: accepted for publication in A&A Letter

Published
2020
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16. The XXL Survey: XXXIX. Polarised radio sources in the XXL-South field

Author

Mark Birkinshaw, J. Delhaize, Vernesa Smolčić, A. Butler, R. A. J. Eyles, Marguerite Pierre, Cathy Horellou, M. Huynh, Cristian Vignali, University of Leicester, University of Bristol [Bristol], University of Zagreb, Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], 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), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of Cape Town, Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), INAF - Osservatorio Astronomico di Bologna (OAB), Istituto Nazionale di Astrofisica (INAF), 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), European Project: 337595,EC:FP7:ERC,ERC-2013-StG,COSMASS(2014), 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), and Università di Bologna [Bologna] (UNIBO)

Subjects
PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, active [Galaxies], 010504 meteorology & atmospheric sciences, Population, galaxies: active, FOS: Physical sciences, galaxies [Radio continuum], Astrophysics, 01 natural sciences, radio continuum: galaxies, law.invention, Telescope, surveys, Coincident, law, 0103 physical sciences, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, education, 010303 astronomy & astrophysics, catalogues, 0105 earth and related environmental sciences, Physics, education.field_of_study, Number density, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Full width at half maximum, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Aims: We investigate the properties of the polarised radio population in the central 6.5 deg$^{2}$ of the XXL-South field observed at 2.1 GHz using the Australia Telescope Compact Array (ATCA) in 81 pointings with a synthesised beam of FWHM 5.2''. We also investigate the ATCA's susceptibility to polarisation leakage. Methods: We performed a survey of a 5.6 deg$^{2}$ subregion and calculated the number density of polarised sources. We derived the total and polarised spectral indices, in addition to comparing our source positions with those of X-ray-detected clusters. We measured the polarisation of sources in multiple pointings to examine leakage in the ATCA. Results: We find 39 polarised sources, involving 50 polarised source components, above a polarised flux density limit of 0.2 mJy at 1.332 GHz. The number density of polarised source components is comparable with recent surveys, although there is an indication of an excess at $\sim1$ mJy. We find that those sources coincident with X-ray clusters are consistent in their properties with regard to the general population. In terms of the ATCA leakage response, we find that ATCA mosaics with beam separation of $\lesssim 2/3$ of the primary beam FWHM have off-axis linear polarisation leakage $\lesssim 1.4$ % at 1.332 GHz., Consists of 14 pages and 9 figures. Accepted to Astronomy & Astrophysics

Published
2020

17. Weak-lensing mass calibration of the Sunyaev–Zel’dovich effect using APEX-SZ galaxy clusters

Author

Kaustuv Basu, Aaron Lee, Martin W. Sommer, Matthias Klein, R. Kneissl, N. W. Halverson, Daniel Ferrusca, P. A. R. Ade, Frank Bertoldi, J. Kennedy, Bradley R. Johnson, Florian Pacaud, Cathy Horellou, Carole Tucker, A. Nagarajan, Amy N. Bender, Christian L. Reichardt, Benjamin Westbrook, and Karl M. Menten

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, FOS: Physical sciences, Sigma, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Covariance, Sunyaev–Zel'dovich effect, 01 natural sciences, Cosmology, Space and Planetary Science, 0103 physical sciences, Cluster sampling, 010303 astronomy & astrophysics, Scaling, Weak gravitational lensing, Galaxy cluster, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The use of galaxy clusters as precision cosmological probes relies on an accurate determination of their masses. However, inferring the relationship between cluster mass and observables from direct observations is difficult and prone to sample selection biases. In this work, we use weak lensing as the best possible proxy for cluster mass to calibrate the Sunyaev-Zel'dovich (SZ) effect measurements from the APEX-SZ experiment. For a well-defined (ROSAT) X-ray complete cluster sample, we calibrate the integrated Comptonization parameter, $Y_{\rm SZ}$, to the weak-lensing derived total cluster mass, $M_{500}$. We employ a novel Bayesian approach to account for the selection effects by jointly fitting both the SZ Comptonization, $Y_{\rm SZ}\text{--}M_{500}$, and the X-ray luminosity, $L_{\rm x}\text{--}M_{500}$, scaling relations. We also account for a possible correlation between the intrinsic (log-normal) scatter of $L_{\rm x}$ and $Y_{\rm SZ}$ at fixed mass. We find the corresponding correlation coefficient to be $r= 0.47_{-0.35}^{+0.24}$, and at the current precision level our constraints on the scaling relations are consistent with previous works. For our APEX-SZ sample, we find that ignoring the covariance between the SZ and X-ray observables biases the normalization of the $Y_{\rm SZ}\text{--}M_{500}$ scaling high by $1\text{--}2\sigma$ and the slope low by $\sim 1\sigma$, even when the SZ effect plays no role in the sample selection. We conclude that for higher-precision data and larger cluster samples, as anticipated from on-going and near-future cluster cosmology experiments, similar biases (due to intrinsic covariances of cluster observables) in the scaling relations will dominate the cosmological error budget if not accounted for correctly., Comment: 27+8 pages. 17+4 figures. Accepted for publication by the Monthly Notices of the Royal Astronomical Society

Published
2018

18. Signatures from a merging galaxy cluster and its AGN population: LOFAR observations of Abell 1682

Author

T. M. Cantwell, Annalisa Bonafede, A. O. Clarke, Huub Röttgering, F. de Gasperin, Jeremy J. Harwood, A. Botteon, Timothy W. Shimwell, Marcus Brüggen, Gianfranco Brunetti, Cathy Horellou, Rossella Cassano, Matthias Hoeft, R. J. van Weeren, George Heald, Anna M. M. Scaife, Clarke A.O., Scaife A.M.M., Shimwell T., Van Weeren R.J., Bonafede A., Heald G., Brunetti G., Cantwell T.M., De Gasperin F., Bruggen M., Botteon A., Hoeft M., Horellou C., Cassano R., Harwood J.J., Rottgering H.J.A., and Astronomy

Subjects
Active galactic nucleus, Radiation mechanisms: non-thermal, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Population, galaxies: halos, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxies: jet, 01 natural sciences, Radio continuum: galaxies, 0103 physical sciences, Cluster (physics), education, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Physics, Spectral index, education.field_of_study, Quasars: supermassive black hole, 010308 nuclear & particles physics, quasars: supermassive black holes, Astronomy and Astrophysics, LOFAR, galaxies: jets, Astrophysics - Astrophysics of Galaxies, Radio halo, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Galaxies: halo, Galaxies: clusters: intracluster medium
Abstract

We present LOFAR data from 110--180~MHz of the merging galaxy cluster Abell 1682, alongside archival optical, radio and X-ray data. Our 6 arc-second resolution images at low frequencies reveal new structures associated with numerous radio galaxies in the cluster. At 20 arc-second resolution we see diffuse emission throughout the cluster over hundreds of kpc, indicating particle acceleration mechanisms are in play as a result of the cluster merger event and powerful active galactic nuclei. We show that a significant part of the cluster emission is from an old radio galaxy with very steep spectrum emission (having a spectral index of $\alpha < -2.5$). Furthermore we identify a new region of diffuse steep spectrum emission ($\alpha < -1.1$) as a candidate for a radio halo which is co-spatial with the centre of the cluster merger. We suggest its origin as a population of old and mildly relativistic electrons left over from radio galaxies throughout the cluster which have been re-accelerated to higher energies by shocks and turbulence induced by the cluster merger event. We also note the discovery of six new giant radio galaxies in the vicinity of Abell 1682., Comment: Accepted in A&A; see journal version for uncompressed figures

Published
2019

19. The intergalactic magnetic field probed by a giant radio galaxy

Author

Joseph R. Callingham, V. Vacca, Johan P. U. Fynbo, G. Brunetti, Keitaro Takahashi, Kasper E. Heintz, Tessa Vernstrom, Franco Vazza, George Heald, Heinz Andernach, Martin J. Hardcastle, Mark Birkinshaw, Jerzy Machalski, E. Carretti, Wendy L. Williams, M. Brueggen, R. J. van Weeren, Marijke Haverkorn, Jeremy J. Harwood, Emanuela Orrú, Shane O'Sullivan, C. L. Van Eck, Maritza A. Lara-López, C. Tasse, James M. Anderson, Błażej Nikiel-Wroczyński, Cathy Horellou, Timothy W. Shimwell, Sui Ann Mao, Leah K. Morabito, 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), and PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), clusters: individual: J1235+5317 [galaxies], Radio galaxy, media_common.quotation_subject, Milky Way, Astronomy, astro-ph.GA, galaxies: active, jets [galaxies], FOS: Physical sciences, Astrophysics, 01 natural sciences, magnetic fields [galaxies], 0103 physical sciences, polarimetric [techniques], 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, radio continuum: galaxies, astro-ph.HE, Line-of-sight, 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, galaxies: clusters: individual: J1235+5317, galaxies: jets, Astrophysics - Astrophysics of Galaxies, Redshift, Universe, galaxies [radio continuum], techniques: polarimetric, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], astro-ph.CO, Intergalactic travel, Astrophysics - High Energy Astrophysical Phenomena, galaxies: magnetic fields, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Cosmological simulations predict that an intergalactic magnetic field (IGMF) pervades the large scale structure (LSS) of the Universe. Measuring the IGMF is important to determine its origin (i.e. primordial or otherwise). Using data from the LOFAR Two Metre Sky Survey (LoTSS), we present the Faraday rotation measure (RM) and depolarisation properties of the giant radio galaxy J1235+5317, at a redshift of $z = 0.34$ and 3.38 Mpc in size. We find a mean RM difference between the lobes of $2.5\pm0.1$ rad/m$^2$ , in addition to small scale RM variations of ~0.1 rad/m$^2$ . From a catalogue of LSS filaments based on optical spectroscopic observations in the local universe, we find an excess of filaments intersecting the line of sight to only one of the lobes. Associating the entire RM difference to these LSS filaments leads to a gas density-weighted IGMF strength of ~0.3 {\mu}G. However, direct comparison with cosmological simulations of the RM contribution from LSS filaments gives a low probability (~5%) for an RM contribution as large as 2.5 rad/m$^2$ , for the case of IGMF strengths of 10 to 50 nG. It is likely that variations in the RM from the Milky Way (on 11' scales) contribute significantly to the mean RM difference, and a denser RM grid is required to better constrain this contribution. In general, this work demonstrates the potential of the LOFAR telescope to probe the weak signature of the IGMF. Future studies, with thousands of sources with high accuracy RMs from LoTSS, will enable more stringent constraints on the nature of the IGMF., Comment: 12 pages, 6 figures, 3 tables. 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

20. 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

21. Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR

Author

E. Buie, Rosita Paladino, Marcus Brüggen, R.-J. Dettmar, Philip Best, Aritra Basu, George Heald, Evan Scannapieco, R. Beck, Elias Brinks, Błażej Nikiel-Wroczyński, Volker Heesen, D. A. Rafferty, L. A. Perez, C. J. Huff, Krzysztof T. Chyzy, Cathy Horellou, K. Sendlinger, and J. G. Woolsey

Subjects
Diffusion equation, Sublinear function, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, astro-ph.GA, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, cosmic rays, magnetic fields [galaxies], 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Physics, 010308 nuclear & particles physics, Star formation, Sigma, Astronomy and Astrophysics, LOFAR, non-thermal [radiation mechanisms], Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, galaxies [radio continuum], Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), star formation [galaxies]
Abstract

Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140 MHz RC emission to the SFR surface density ($\Sigma_{\rm SFR}$) at 1 kpc scale. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw-Frequency ARray (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio $\Sigma_{\rm SFR}$ maps using the Condon relation. We compared these maps with hybrid $\Sigma_{\rm SFR}$ maps from a combination of GALEX far-ultraviolet and Spitzer 24 $\mu\rm m$ data using plots tracing the relation at $1.2\times 1.2$-kpc$^2$ resolution. The RC emission is smoothed with respect to the hybrid $\Sigma_{\rm SFR}$ owing to the transport of cosmic-ray electrons (CREs). This results in a sublinear relation $(\Sigma_{\rm SFR})_{\rm RC} \propto [(\Sigma_{\rm SFR})_{\rm hyb}]^{a}$, where $a=0.59\pm 0.13$ (140 MHz) and $a=0.75\pm 0.10$ (1365 MHz). Both relations have a scatter of $\sigma = 0.3~\rm dex$. If we restrict ourselves to areas of young CREs ($\alpha > -0.65$; $I_\nu \propto \nu^\alpha$), the relation becomes almost linear at both frequencies with $a\approx 0.9$ and a reduced scatter of $\sigma = 0.2~\rm dex$. We then simulate the effect of CRE transport by convolving the hybrid $\Sigma_{\rm SFR}$ maps with a Gaussian kernel until the RC-SFR relation is linearised; CRE transport lengths are $l=1$-5 kpc. Solving the CRE diffusion equation, we find diffusion coefficients of $D=(0.13$-$1.5) \times 10^{28} \rm cm^2\,s^{-1}$ at 1 GeV. A RC-SFR relation at $1.4$ GHz can be exploited to measure SFRs at redshift $z \approx 10$ using $140$ MHz observations., Comment: 9 figures, 6 tables and 17 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

22. 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

23. Stellar feedback in dwarf irregular galaxies with radio continuum observations

Author

Cathy Horellou, Andrew Fletcher, Krzysztof T. Chyzy, Aritra Basu, George Heald, Matthias Hoeft, Elias Brinks, and Volker Heesen

Subjects
Physics, 010308 nuclear & particles physics, Star formation, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, LOFAR, Astrophysics, Electron, 01 natural sciences, Spectral line, Radio halo, Space and Planetary Science, 0103 physical sciences, Irregular galaxy, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy
Abstract

Low-mass dwarf irregular galaxies are subject to outflows, in which cosmic rays may play a very important role; they can be traced via their electron component, the cosmic ray electrons (CRe), in the radio continuum as non-thermal synchrotron emission. With the advent of sensitive low-frequency observations, such as with the Low-Frequency Array (LOFAR), we can trace CRe far away from star formation sites. Together with GHz-observations, such as with the Very Large Array (VLA), we can study spatially resolved radio continuum spectra at matched angular resolution and sensitivity. Here, we present results from our 6-GHz VLA survey of 40 nearby dwarf galaxies and our LOFAR study of the nearby starburst dwarf irregular galaxy IC 10. We explore the relation of RC emission with star formation tracers and study in IC 10 the nature of a low-frequency radio halo, which we find to be the result of a galactic wind.

Published
2019

24. The XXL Survey

Author

Vernesa Smolčić, Cathy Horellou, Christophe Benoist, Konstantinos Kolokythas, Bianca M. Poggianti, Mark Birkinshaw, Cristian Vignali, M. E. Ramos-Ceja, H. J. A. Röttgering, Somak Raychaudhury, César A. Caretta, C. Adami, J. Delhaize, L. Tolliner, F. Karlsson, Sotiria Fotopoulou, Chiara Ferrari, Huib Intema, Andreas Nilsson, L. Chiappetti, Florian Pacaud, Marguerite Pierre, C. Krook, V. Guglielmo, Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], Leiden Observatory [Leiden], Universiteit Leiden, University of Zagreb, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), 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), University of Bristol [Bristol], INAF-IASF Milano, Istituto Nazionale di Astrofisica (INAF), Aristotle University of Thessaloniki, North-West University [South Aftrica] (NWU), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), INAF - Osservatorio Astronomico di Padova (OAPD), Horellou, C., Intema, H.T., Smolčić, V., Nilsson, A., Karlsson, F., Krook, C., Tolliner, L., Adami, C., Benoist, C., Birkinshaw, M., Caretta, C., Chiappetti, L., Delhaize, J., Ferrari, C., Fotopoulou, S., Guglielmo, V., Kolokythas, K., Pacaud, F., Pierre, M., Poggianti, B.M., Ramos-Ceja, M.E., Raychaudhury, S., Röttgering, H.J.A., and Vignali, C.

Subjects
Radiation mechanisms: non-thermal, active [Galaxies], PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, Radio galaxy, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, galaxies [Radio continuum], Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio continuum: galaxies, Supercluster, Galaxies: magnetic field, 0103 physical sciences, Cluster (physics), NATURAL SCIENCES. Physics. Astronomy and Astrophysics, data analysis [Methods], 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Physics, Giant Metrewave Radio Telescope, non-thermal [Radiation mechanisms], 010308 nuclear & particles physics, Visual examination, magnetic fields [Galaxies], Astronomy and Astrophysics, Galaxies: active, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Methods: data analysi
Abstract

We show how the XXL multiwavelength survey can be used to shed light on radio galaxies and their environment. Two prominent radio galaxies were identified in a visual examination of the mosaic of XXL-North obtained with the Giant Metrewave Radio Telescope at 610MHz. Counterparts were searched for in other bands. Spectroscopic redshifts from the GAMA database were used to identify clusters and/or groups of galaxies, estimate their masses with the caustic method, and quantify anisotropies in the surrounding galaxy distribution via a Fourier analysis. Both radio galaxies are of FR I type and are hosted by early-type galaxies at a redshift of 0.138. The first radio source, named the Exemplar, has a physical extent of about 400 kpc; it is located in the cluster XLSSC112, which has a temperature of about 2 keV, a total mass of about $10^{14} M_\odot$, and resides in an XXL supercluster with eight known members. The second source, named the Double Irony, is a giant radio galaxy with a total length of about 1.1 Mpc. Its core coincides with a cataloged point-like X-ray source, but no extended X-ray emission from a surrounding galaxy cluster was detected. However, from the optical data we determined that the host is the brightest galaxy in a group that is younger, less virialized, and less massive than the Exemplar's cluster. A friends-of-friends analysis showed that the Double Irony's group is a member of the same supercluster as the Exemplar. There are indications that the jets and plumes of the Double Irony have been deflected by gas associated with the surrounding galaxy distribution. Another overdensity of galaxies (the tenth) containing a radio galaxy was found to be associated with the supercluster. Radio galaxies can be used to find galaxy clusters/groups that are below the current sensitivity of X-ray surveys., 23 pages, 16 figures, accepted for publication in A&A

Published
2018

25. Untangling Cosmic Magnetic Fields: Faraday Tomography at MetreWavelengths with LOFAR

Author

Cathy Horellou, Shane O'Sullivan, Cyril Tasse, Marcus Brüggen, Martin J. Hardcastle, Cameron Van Eck, Marijke Haverkorn, George Heald, Valentina Vacca, and Timothy W. Shimwell

Subjects
Physics, COSMIC cancer database, law, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, LOFAR, Tomography, Astrophysics::Cosmology and Extragalactic Astrophysics, Faraday cage, astronomy_astrophysics, law.invention, Magnetic field
Abstract

The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio polarisation observations. In particular, observations at metre-wavelengths provide significantly better Faraday depth accuracies compared to traditional cm-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengths (MHz frequencies). In this work, Faraday tomography is used to characterise the Faraday rotation properties of polarised sources found in data from the LOFAR Two-Metre Sky Survey (LoTSS). Of the 76 extragalactic polarised sources analysed here, we find that all host a radio-loud AGN. The majority of the sources (∼64%) are large FRII radio galaxies with a median projected linear size of 710 kpc and median radio luminosity at 144 MHz of 4 × 10^26 W/Hz. In several cases, both hotspots are detected in polarisation at an angular resolution of ∼20". One such case allowed a study of intergalactic magnetic fields on scales of 3.4 Mpc. Other detected source types include an FRI radio galaxy and at least 8 blazars. Most sources display simple Faraday spectra, however, we highlight one blazar that displays a complex Faraday spectrum, with two close peaks in the Faraday dispersion function.

Published
2018

26. Galaxy cluster scaling relations measured with APEX-SZ

Author

Daniel Ferrusca, W. L. Holzapfel, Paul L. Richards, Helmuth Spieler, Frank Bertoldi, Bradley R. Johnson, D. Schwan, Peter A. R. Ade, Cathy Horellou, J. Kennedy, J. Mehl, M. Klein, S. Burkutean, Zigmund Kermish, M. A. Dobbs, Trevor Lanting, Martin W. Sommer, Karl M. Menten, R. Schaaf, Christian L. Reichardt, Florian Pacaud, John Clarke, Daniel Flanigan, Carole Tucker, Kaustuv Basu, Daniel Dahlin, N. W. Halverson, A. Nagarajan, Amy N. Bender, Benjamin Westbrook, Dirk Muders, R. Kneissl, and Aaron Lee

Subjects
Normalization (statistics), Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Cosmic background radiation, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 7. Clean energy, 01 natural sciences, Measure (mathematics), Cosmology, Space and Planetary Science, Intracluster medium, 0103 physical sciences, Cluster (physics), 010303 astronomy & astrophysics, Scaling, Galaxy cluster, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present thermal Sunyaev-Zel'dovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization $Y$ to estimate the total thermal energy of the intracluster medium (ICM). We compare the measured $Y$ values to X-ray observables of the ICM from the literature (cluster gas mass $M_{\rm{gas}}$, temperature $T_X$, and $Y_X =M_{\rm{gas}}T_X$) that relate to total cluster mass. We measure power law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for three subsamples within the set of 42 clusters that have uniform X-ray analysis in the literature. We observe that differences between these X-ray analyses introduce significant variability into the measured scaling relations, particularly affecting the normalization. For all three subsamples, we find results consistent with a self-similar model of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we measure an intrinsic scatter of $\sim28$ per cent in the $Y-Y_X\,$ scaling relation for all three subsamples., Comment: 17 pages, 4 figures, submitted to MNRAS

Published
2016

27. LOFAR, VLA, and Chandra Observations of the Toothbrush Galaxy Cluster

Author

H. J. A. Röttgering, Christine Jones, Laura Birzan, William A. Dawson, Georgiana A. Ogrean, J. Sabater, Judith H. Croston, Torsten A. Ensslin, S. S. Murray, T. J. Dijkema, Martin J. Hardcastle, S. S. Sridhar, S. van der Tol, Lawrence Rudnick, Roberto Pizzo, Marcus Brüggen, Rossella Cassano, Cathy Horellou, Maaijke Mevius, Aurora Simionescu, William R. Forman, Craig L. Sarazin, George Heald, Glenn J. White, Krzysztof T. Chyzy, Emanuela Orrú, Andra Stroe, G. K. Miley, Annalisa Bonafede, Wendy L. Williams, D. A. Rafferty, Hubertus Intema, G. Brunetti, Timothy W. Shimwell, Felipe Andrade-Santos, R. J. van Weeren, Philip Best, Chiara Ferrari, Matthias Hoeft, Ralph P. Kraft, Matt J. Jarvis, F. de Gasperin, Astronomy, Van Weeren, R.J., Brunetti, G., Brüggen, M., Andrade-Santos, F., Ogrean, G.A., Williams, W.L., Röttgering, H.J.A., Dawson, W.A., Forman, W.R., Gasperin, F. De, Hardcastle, M.J., Jones, C., Miley, G.K., Rafferty, D.A., Rudnick, L., Sabater, J., Sarazin, C.L., Shimwell, T.W., Bonafede, A., Best, P.N., Birzan, L., Cassano, R., Chyzy, K.T., Croston, J.H., Dijkema, T.J., Enßlin, T., Ferrari, C., Heald, G., Hoeft, M., Horellou, C., Jarvis, M.J., Kraft, R.P., Mevius, M., Intema, H.T., Murray, S.S., Orrú, E., Pizzo, R., Sridhar, S.S., Simionescu, A., Stroe, A., Tol, S. Van Der, and White, G.J.

Subjects
clusters: individual: RX J0603.3+4214 [galaxies], Cosmology and Nongalactic Astrophysics (astro-ph.CO), galaxies: clusters: intracluster medium, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, galaxies: clusters: individual: RX J0603.3+4214, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio relics, 0103 physical sciences, education, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, large-scale structure of universe, education.field_of_study, Spectral index, 010308 nuclear & particles physics, galaxies: clusters: individual (RX J0603.3+4214), largescale structure of universe, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, radiation mechanisms: non-thermal, non-thermal [radiation mechanisms], X-rays: galaxies: cluster, Particle acceleration, Radio halo, clusters: intracluster medium [galaxies], Space and Planetary Science, X-rays: galaxies: clusters, large-scale structure of Universe, galaxies: clusters [X-rays], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

著者人数: 42名, Accepted: 2016-01-18, 資料番号: SA1160090000

Published
2016

28. Reliable detection and characterization of low-frequency polarized sources in the LOFAR M51 field

Author

Stephen Bourke, D. D. Mulcahy, A. Neld, A. Horneffer, Andrew Fletcher, John Conway, Krzysztof T. Chyzy, C. L. Van Eck, George Heald, Błażej Nikiel-Wroczyński, Cathy Horellou, Tobia Carozzi, S. S. Sridhar, Jamie Farnes, Marijke Haverkorn, R. Beck, Rosita Paladino, and Astronomy

Subjects
RADIO-SOURCES, individual: M51 [galaxies], Astronomy, FOS: Physical sciences, GALAXY M51, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, DETECTION THRESHOLDS, 01 natural sciences, law.invention, REIONIZATION WINDOWS, symbols.namesake, Optics, magnetic fields [galaxies], law, polarimetric [techniques], 0103 physical sciences, Faraday effect, data analysis [methods], Faraday cage, 010303 astronomy & astrophysics, radio continuum: galaxies, Physics, polarization, LINEAR-POLARIZATION, Line-of-sight, 010308 nuclear & particles physics, business.industry, Linear polarization, MAGNETIC-FIELD, Astronomy and Astrophysics, LOFAR, FARADAY-ROTATION, Polarization (waves), methods: data analysis, Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Square degree, techniques: polarimetric, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxies: individual: M51, symbols, MILKY-WAY, Radio frequency, galaxies: magnetic fields, business, ROTATION MEASURE SYNTHESIS, FALSE-DISCOVERY RATE
Abstract

The new generation of broad-band radio continuum surveys will provide large data sets with polarization information. New algorithms need to be developed to extract reliable catalogs of linearly polarized sources that can be used to characterize those sources and produce a dense rotation measure (RM) grid to probe magneto-ionized structures along the line of sight via Faraday rotation. The aim of the paper is to develop a computationally efficient and rigorously defined source-finding algorithm for linearly polarized sources. We used a calibrated data set from the LOw Frequency ARray (LOFAR) at 150 MHz centered on the nearby galaxy M51 to search for polarized background sources. With a new imaging software, we re-imaged the field at a resolution of 18''x15'' and cataloged a total of about 3000 continuum sources within 2.5 degrees of the center of M51. We made small Stokes Q and U images centered on each source brighter than 100 mJy in total intensity (201 sources) and used RM synthesis to create corresponding Faraday cubes that were analyzed individually. For each source, the noise distribution function was determined from a subset of measurements at high Faraday depths where no polarization is expected; the peaks in polarized intensity in the Faraday spectrum were identified and the p-value of each source was calculated. Finally, the false discovery rate method was applied to the list of p-values to produce a list of polarized sources and quantify the reliability of the detections. We also analyzed sources fainter than 100 mJy but that were reported as polarized in the literature at at least another radio frequency. Of the 201 sources that were searched for polarization, 6 polarized sources were detected confidently (with a false discovery rate of 5 percent). This corresponds to a number density of 1 polarized source per 3.3 square degrees, or 0.3 source/square degree. [Abridged], 17 pages, 11 figures, accepted for publication in A&A

Published
2018

29. Investigation of the cosmic ray population and magnetic field strength in the halo of NGC 891

Author

Nima Razavi-Ghods, Keith Grainge, S. S. Sridhar, D. D. Mulcahy, Paul F. Scott, Błażej Nikiel-Wroczyński, Philip Schmidt, Aritra Basu, George Heald, Y. Perrot, A. Horneffer, Fatemeh Tabatabaei, Anna M. M. Scaife, Marita Krause, Rainer Beck, R. J. Dettmar, M. Iacobelli, Cathy Horellou, Rosita Paladino, David Titterington, Marijke Haverkorn, Richard G. Strom, T. M. Cantwell, J. Hickish, Volker Heesen, Krzysztof T. Chyzy, S. H. Carey, and Astronomy

Subjects
J.2, Arcminute Microkelvin Imager, Astronomy, galaxies: halos, Astrophysics, magnetic fields, GALACTIC WIND, 01 natural sciences, magnetic fields [galaxies], galaxies, individual, EDGE-ON GALAXIES, 010303 astronomy & astrophysics, Physics, Spectral index, education.field_of_study, magnetic fields / cosmic rays / radio continuum, NGC 891 / galaxies, halos [galaxies], Spectral energy distribution, Halo, galaxies: magnetic fields, galaxies: ISM, ARCMINUTE MICROKELVIN IMAGER, Astrophysics::High Energy Astrophysical Phenomena, Population, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, cosmic rays, RADIO-CONTINUUM OBSERVATIONS, SPIRAL GALAXY NGC-891, 0103 physical sciences, galaxies: individual: NGC 891, STAR-FORMING GALAXIES, NEARBY GALAXIES, education, Astrophysics::Galaxy Astrophysics, radio continuum: galaxies, Spiral galaxy, ISM [galaxies], INTERSTELLAR-MEDIUM, 010308 nuclear & particles physics, halos / galaxies, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies [radio continuum], ISM / galaxies, Interstellar medium, 85-05, SPECTRAL ENERGY-DISTRIBUTION, Space and Planetary Science, individual: NGC 891 [galaxies], Astrophysics of Galaxies (astro-ph.GA), X-RAY
Abstract

Low-frequency radio continuum observations of edge-on galaxies are ideal to study cosmic-ray electrons (CREs) in halos via radio synchrotron emission and to measure magnetic field strengths. We obtained new observations of the edge-on spiral galaxy NGC 891 at 129-163 MHz with the LOw Frequency ARray (LOFAR) and at 13-18 GHz with the Arcminute Microkelvin Imager (AMI) and combine them with recent high-resolution Very Large Array (VLA) observations at 1-2 GHz, enabling us to study the radio continuum emission over two orders of magnitude in frequency. The spectrum of the integrated nonthermal flux density can be fitted by a power law with a spectral steepening towards higher frequencies or by a curved polynomial. Spectral flattening at low frequencies due to free-free absorption is detected in star-forming regions of the disk. The mean magnetic field strength in the halo is 7 +- 2 $\mu$G. The scale heights of the nonthermal halo emission at 146 MHz are larger than those at 1.5 GHz everywhere, with a mean ratio of 1.7 +- 0.3, indicating that spectral ageing of CREs is important and that diffusive propagation dominates. The halo scale heights at 146 MHz decrease with increasing magnetic field strengths which is a signature of dominating synchrotron losses of CREs. On the other hand, the spectral index between 146 MHz and 1.5 GHz linearly steepens from the disk to the halo, indicating that advection rather than diffusion is the dominating CRE transport process. This issue calls for refined modelling of CRE propagation., Comment: Accepted for publication in Astronomy & Astrophysics

Published
2018

30. The 'Cosmic Seagull': a highly magnified disk-like galaxy at z~2.8 behind the Bullet Cluster

Author

D. Gunawan, Omar López-Cruz, Edo Ibar, John H. Black, Thomas M. Hughes, Juan Molina, Tomás Verdugo, Veronica Motta, Cathy Horellou, Mark Birkinshaw, and Juan Magaña

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Stellar mass, galaxies [submillimeter], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Submillimeter Array, 0103 physical sciences, clusters: individual (1ES0657-558) [galaxies], 010303 astronomy & astrophysics, Galaxy rotation curve, evolution [galaxies], Astrophysics::Galaxy Astrophysics, Physics, ISM [galaxies], 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Baryon, Space and Planetary Science, strong [gravitational lensing], Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, Millimeter, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present Atacama Large Millimeter/submillimeter Array measurements of the `Cosmic Seagull', a strongly magnified galaxy at z=2.7779 behind the Bullet Cluster. We report CO(3-2) and continuum 344~$\mu$m (rest-frame) data at one of the highest differential magnifications ever recorded at submillimeter wavelengths ($\mu$ up to ~50), facilitating a characterization of the kinematics of a rotational curve in great detail (at ~620 pc resolution in the source plane). We find no evidence for a decreasing rotation curve, from which we derive a dynamical mass of ($6.3\pm0.7)\times10^{10} M_{\odot}$ within $r = 2.6\pm0.1$ kpc. The discovery of a third, unpredicted, image provides key information for a future improvement of the lensing modeling of the Bullet Cluster and allows a measure of the stellar mass, $1.6^{+1.9}_{-0.86}\times10^{10} M_{\odot}$, unaffected by strong differential magnification. The baryonic mass is is expected to be dominated by the molecular gas content ($f_{gas} \leq 80 \pm 20$ \%) based on an $M_{H_2}$ mass estimated from the difference between dynamical and stellar masses. The star formation rate is estimated via the spectral energy distribution ($SFR = 190 \pm 10 M_{\odot}/yr$), implying a molecular gas depletion time of $0.25\pm0.08$ Gyr., Comment: 14 pages LaTeX using ApJLetter macros, author final version accepted, 4 figures

Published
2018
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31. Exploring the making of a galactic wind in the star-bursting dwarf irregular galaxy IC 10 with LOFAR

Author

Luke Hindson, Rainer Beck, D. Rafferty, Fatemeh Tabatabaei, Jonathan Westcott, Rosita Paladino, Błażej Nikiel-Wroczyński, Elias Brinks, George Heald, Marcus Brüggen, A. Horneffer, Aritra Basu, Andrew Fletcher, R. J. Dettmar, Krzysztof T. Chyzy, Matthias Hoeft, Anna M. M. Scaife, Cathy Horellou, Volker Heesen, and Astronomy

Subjects
COSMIC-RAY TRANSPORT, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, MASS, 01 natural sciences, STAR-FORMATION, magnetic fields [galaxies], cosmic rays, 0103 physical sciences, PHOTOMETRY, HALOES, NEARBY GALAXIES, IC-10, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, radio continuum: galaxies, COSMIC cancer database, RADIO, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, LOFAR, Escape velocity, Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Galaxy, Radio halo, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Irregular galaxy, galaxies: magnetic fields, SKY SURVEY
Abstract

Low-mass galaxies are subject to strong galactic outflows, in which cosmic rays may play an important role, they can be best traced with low-frequency radio continuum observations, which are less affected by spectral ageing. We present a study of the nearby star burst dwarf irregular galaxy IC 10 using observations at 140 MHz with the LOw-Frequency ARray (LOFAR), at 1580 MHz with the Very Large Array (VLA) and at 6200 MHz with the VLA and the 100-m Effelsberg telescope. We find that IC 10 has a low-frequency radio halo, which manifests itself as a second component (thick disc) in the minor axis profiles of the non-thermal radio continuum emission at 140 and 1580 MHz. These profiles are then fitted with 1D cosmic-ray transport models for pure diffusion and advection. We find that a diffusion model fits best, with a diffusion coefficient of $D=(0.4$-$0.8) \times 10^{26}(E/{\rm GeV})^{0.5}~{\rm cm^2\,s^{-1}}$, which is at least an order of magnitude smaller than estimates both from anisotropic diffusion and the diffusion length. In contrast, advection models, which cannot be ruled out due to the mild inclination, while providing poorer fits, result in advection speeds close to the escape velocity of $\approx$$50~\rm km\,s^{-1}$, as expected for a cosmic-ray driven wind. Our favoured model with an accelerating wind provides a self-consistent solution, where the magnetic field is in energy equipartition with both the warm neutral and warm ionized medium with an important contribution from cosmic rays. Consequently, cosmic rays can play a vital role for the launching of galactic winds in the disc--halo interface., Comment: 10 pages, 5 colour figures, 1 table. Accepted by MNRAS

Published
2018
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32. The XXL Survey. XXIX. GMRT 610 MHz continuum observations

Author

Ray P. Norris, Vernesa Smolčić, Chiara Ferrari, Konstantinos Kolokythas, Sean L. McGee, Cathy Horellou, Chris Lidman, M. Bondi, J. Delhaize, Mladen Novak, L. Chiappetti, Malcolm N. Bremer, Huib Intema, Cyril Tasse, Huub Röttgering, Bruno Šlaus, Somak Raychaudhury, Marguerite Pierre, Mark Birkinshaw, Paolo Ciliegi, Wendy L. Williams, University of Zagreb, Leiden Observatory [Leiden], Universiteit Leiden, Inter-University Centre for Astronomy and Astrophysics [Pune] (IUCAA), University of Birmingham [Birmingham], Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Istituto di Astrofisica Spaziale e Fisica Cosmica - Milano (IASF-MI), Istituto Nazionale di Astrofisica (INAF), University of Bristol [Bristol], INAF - Osservatorio Astronomico di Bologna (OABO), Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), Australian Astronomical Observatory, Western Sydney University, CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), 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), 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), University of Hertfordshire [Hatfield] (UH), The Saclay group acknowledges long-term support from the Centre National d’Études Spatiales (CNES)., XXL, XMM Very Large Programme, European Project: 333654,EC:FP7:PEOPLE,FP7-PEOPLE-2012-CIG,AGN FEEDBACK(2013), European Project: 337595,EC:FP7:ERC,ERC-2013-StG,COSMASS(2014), Universiteit Leiden [Leiden], 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)-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), Onsala Space Observatory, Université Côte d'Azur (UCA), Western Sydney University (UWS), and PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Active galactic nucleus, Field (physics), PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Square (algebra), surveys, 0103 physical sciences, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, Continuum (set theory), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Giant Metrewave Radio Telescope, 010308 nuclear & particles physics, catalogs, surveys, galaxies: active, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrometry, Astrophysics - Astrophysics of Galaxies, Square degree, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], catalogs
Abstract

We present the 25 square-degree GMRT-XXL-N 610 MHz radio continuum survey, conducted at 50~cm wavelength with the Giant Metrewave Radio Telescope (GMRT) towards the XXL Northern field (XXL-N). We combined previously published observations of the XMM-Large Scale Structure (XMM-LSS) field, located in the central part of XXL-N, with newly conducted observations towards the remaining XXL-N area, and imaged the combined data-set using the Source Peeling and Atmospheric Modeling ({\sc SPAM}) pipeline. The final mosaic encompasses a total area of $30.4$ square degrees, with ${\rm rms}, Comment: 11 pages, 13 figures, 1 table; to appear in A&A (XXL special issue)

Published
2018

33. The XXL Survey. XXX. Characterisation of the XLSSsC N01 supercluster and analysis of the galaxy stellar populations

Author

August E. Evrard, Angela Bongiorno, Cathy Horellou, Mark Birkinshaw, Elias Koulouridis, Andrii Elyiv, R. J. Tuffs, Sophie Maurogordato, A. Iovino, Fabio Gastaldello, L. Guennou, Aaron S. G. Robotham, Florian Pacaud, Paul Giles, M. E. Ramos Ceja, Jacopo Fritz, Stéphane Paltani, Vernesa Smolčić, T. Sadibekova, Matt S. Owers, Cristian Vignali, Marguerite Pierre, J. Willis, V. Guglielmo, Bianca M. Poggianti, César A. Caretta, Ivan K. Baldry, Andrew M. Hopkins, Trevor J. Ponman, Meiert W. Grootes, Michael J. I. Brown, Manolis Plionis, C. Adami, L. Chiappetti, Alberto Moretti, Benedetta Vulcani, Simon P. Driver, University of St Andrews. School of Physics and Astronomy, Guglielmo, V., Poggianti, B.M., Vulcani, B., Moretti, A., Fritz, J., Gastaldello, F., Adami, C., Caretta, C.A., Willis, J., Koulouridis, E., Ramos Ceja, M.E., Giles, P., Baldry, I., Birkinshaw, M., Bongiorno, A., Brown, M., Chiappetti, L., Driver, S., Elyiv, A., Evrard, A., Grootes, M., Guennou, L., Hopkins, A., Horellou, C., Iovino, A., Maurogordato, S., Owers, M., Pacaud, F., Paltani, S., Pierre, M., Plionis, M., Ponman, T., Robotham, A., Sadibekova, T., Smolčić, V., Tuffs, R., and Vignali, C.

Subjects
PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, Stellar population, FOS: Physical sciences, Perturbation (astronomy), large-scale structure of Universe, X-rays: galaxies: clusters, galaxies: groups: general, galaxies: evolution, galaxies: star formation, galaxies: stellar content, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, star formation [Galaxies], Virial theorem, Supercluster, Large-scale structure of the universe, 0103 physical sciences, Cluster (physics), NATURAL SCIENCES. Physics. Astronomy and Astrophysics, QB Astronomy, 010303 astronomy & astrophysics, QC, Astrophysics::Galaxy Astrophysics, QB, Physics, 85A04, 010308 nuclear & particles physics, Star formation, Astronomy and Astrophysics, 3rd-DAS, evolution [Galaxies], Astrophysics - Astrophysics of Galaxies, Galaxy, groups: general [Galaxies], QC Physics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, stellar content [Galaxies], galaxies: clusters [X-rays]
Abstract

Superclusters form from the largest enhancements in the primordial density perturbation field and extend for tens of Mpc, tracing the large-scale structure of the Universe. We characterise XLSSsCN01, a rich supercluster at z~0.3 detected in the XXL Survey, composed of X-ray clusters of different virial masses and luminosities. As one of the first studies on this topic, we investigate the stellar populations of galaxies in different environments in the supercluster region. We study a magnitude-limited (r10.8) of galaxies in the virialised region and in the outskirts of 11 XLSSsCN01 clusters, in high- and low-density field. We compute the stellar population properties of galaxies using spectral energy distribution and spectral fitting techniques, and study the dependence of star formation rates (SFR), colours, and stellar ages on environment. For r-12 and with (g-r)_rf10.8, no trends with environment emerge, as massive galaxies are mostly already passive in all environments. No differences among low- and high-density field members and cluster members emerge in the sSFR-mass relation. The luminosity-weighted age-mass relation of the passive populations within cluster virial radii show signatures of recent environmental quenching. The study of luminous and massive galaxies in this supercluster shows that while environment has a prominent role in determining the fractions of SFing/blue galaxies, its effects on the star formation activity in SFing galaxies are negligible., 16 pages, 10 figures, 2 tables, accepted for publication in A&A

Published
2018

34. The XXL Survey: XXV. Cosmological analysis of the C1 cluster number counts

Author

C. Adami, T. Sadibekova, Florian Pacaud, C. Lidman, Sinan Aliş, Jon Willis, Bruno Altieri, Mark Birkinshaw, J. P. Le Fevre, Mauro Sereno, Lauro Moscardini, Bianca M. Poggianti, Sophie Maurogordato, F. Gastaldello, Manolis Plionis, A. Iovino, I. Valtchanov, Paul Giles, S. Galli, Jean-Baptiste Melin, M. Lieu, Marguerite Pierre, L. Faccioli, Ben J Maughan, August E. Evrard, L. Chiappetti, Emanuela Pompei, Cathy Horellou, Elias Koulouridis, 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), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Observatoire de la Côte d'Azur (OCA), Centre National de la Recherche Scientifique (CNRS), XXL, 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), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), 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), Pacaud, F., Pierre, M., Melin, J.-B., Adami, C., Evrard, A.E., Galli, S., Gastaldello, F., Maughan, B.J., Sereno, M., Alis, S., Altieri, B., Birkinshaw, M., Chiappetti, L., Faccioli, L., Giles, P.A., Horellou, C., Iovino, A., Koulouridis, E., Le Fèvre, J.-P., Lidman, C., Lieu, M., Maurogordato, S., Moscardini, L., Plionis, M., Poggianti, B.M., Pompei, E., Sadibekova, T., Valtchanov, I., Willis, J.P., and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
Cosmological parameter, Cold dark matter, Cosmology and Nongalactic Astrophysics (astro-ph.CO), galaxies: clusters: intracluster medium, Large-scale structure of Universe, Cosmic microwave background, Cosmological parameters, FOS: Physical sciences, Context (language use), Astrophysics, clusters: intracluster medium [Galaxies], Astrophysics::Cosmology and Extragalactic Astrophysics, Surveys, 01 natural sciences, Cosmology, symbols.namesake, surveys, 0103 physical sciences, Planck, cosmological parameters, Survey, 010303 astronomy & astrophysics, Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astronomy and Astrophysic, X-rays: galaxies: cluster, Redshift, Galaxy, Space and Planetary Science, X-rays: galaxies: clusters, symbols, Cluster sampling, galaxies: clusters [X-rays], large-scale structure of Universe, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Context. We present an estimation of cosmological parameters with clusters of galaxies. Aims. We constrain the $\Omega_m$, $\sigma_8$, and $w$ parameters from a stand-alone sample of X-ray clusters detected in the 50 deg$^2$ XMM-XXL survey with a well-defined selection function. Methods. We analyse the redshift distribution of a sample comprising 178 high S/N clusters out to a redshift of unity. The cluster sample scaling relations are determined in a self-consistent manner. Results. In a lambda cold dark matter ($\Lambda$CDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the Planck S-Z clusters for a totally different sample (mass/redshift range, selection biases, and scaling relations). However, with this preliminary sample and current mass calibration uncertainty, we find no inconsistency with the Planck CMB cosmology. If we relax the $w$ parameter, the Planck CMB uncertainties increase by a factor of $\sim$10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on $\Omega_m$=0.316$\pm$0.060, $\sigma_8$=0.814$\pm$0.054, and $w$=-1.02$\pm$0.20. Conclusions. This first self-consistent cosmological analysis of a sample of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger sample extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3., Comment: 11 pages, 5 figures, 5 tables, accepted as a letter by Astronomy & Astrophysics

Published
2018

35. Source finding in linear polarization for LOFAR, and SKA predecessor surveys, using Faraday moments

Author

H. Junklewitz, C. L. Van Eck, A. Horneffer, D. D. Mulcahy, Michiel A. Brentjens, Jamie Farnes, Marijke Haverkorn, C. J. Riseley, Rosita Paladino, Valentina Vacca, Cathy Horellou, D.I. Jones, and George Heald

Subjects
media_common.quotation_subject, Astronomy, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Standard deviation, law.invention, Radio telescope, law, 0103 physical sciences, Faraday cage, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), media_common, Physics, 010308 nuclear & particles physics, Linear polarization, Bandwidth (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Polarization (waves), Space and Planetary Science, Sky, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The optimal source-finding strategy for linear polarization data is an unsolved problem, with many inhibitive factors imposed by the technically-challenging nature of polarization observations. Such an algorithm is essential for Square Kilometre Array (SKA) pathfinder surveys, such as the Multifrequency Snapshot Sky Survey (MSSS) with the LOw Frequency ARray (LOFAR), as data volumes are significant enough to prohibit manual inspection. We present a new strategy of `Faraday Moments' for source-finding in linear polarization with LOFAR, using the moments of the frequency-dependent full-Stokes data (i.e. the mean, standard deviation, skewness, and excess kurtosis). Through simulations of the sky, we find that moments can identify polarized sources with a high completeness: 98.5% at a signal-to-noise of 5. While the method has low reliability, Rotation Measure (RM) Synthesis can be applied per candidate source to filter out instrumental and spurious detections. This combined strategy will result in a complete and reliable catalogue of polarized sources that includes the full sensitivity of the observational bandwidth. We find that the technique can reduce the number of pixels on which RM Synthesis needs to be performed by a factor of $\approx1\times10^{5}$ for source distributions anticipated with modern radio telescopes. Through tests on LOFAR data, we find that the technique works effectively in the presence of diffuse emission. Extensions of this method are directly applicable to other upcoming radio surveys such as the POlarization Sky Survey of the Universe's Magnetism (POSSUM) with the Australia Square Kilometre Array Pathfinder (ASKAP), and the SKA itself., Accepted for publication in MNRAS

Published
2017

36. 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

37. Exploring the properties of low-frequency radio emission and magnetic fields in a sample of compact galaxy groups using the LOFAR Two-Metre Sky Survey (LoTSS)

Author

Błażej Nikiel-Wroczyński, A. Becker, Marek Jamrozy, Cathy Horellou, Timothy W. Shimwell, N. Herrera Ruiz, R.-J. Dettmar, Dominik J. Bomans, S. Blex, Cyril Tasse, George Heald, A. Berger, Rainer Beck, Volker Heesen, Krzysztof T. Chyzy, Rosita Paladino, Arpad Miskolczi, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
media_common.quotation_subject, FOS: Physical sciences, groups, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, magnetic fields, Low frequency, 01 natural sciences, radio continuum, galaxies -galaxies, magnetic fields [galaxies], Galaxy group, 0103 physical sciences, Metre, magnetic fields -magnetic fields, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, general -galaxies, media_common, [PHYS]Physics [physics], Physics, groups: general [galaxies], 010308 nuclear & particles physics, Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Sample (graphics), galaxies [radio continuum], Galaxy, Magnetic field, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We use the LOFAR Two-metre Sky Survey (LoTSS) Data Release I to identify the groups of galaxies (and individual galaxies) from the Hickson Compact Groups and Magnitude Limited Compact Groups samples that emit at the frequency of 150\,MHz, characterise their radio emission (extended or limited to the galaxies), and compare new results to earlier observations and theoretical predictions. The detection of 73 systems (and 7 more -- probably) out of 120, of which as many as 17 show the presence of extended radio structures, confirms the previous hypothesis of the common character of the magnetic field inside galaxy groups and its detectability. In order to investigate the future potential of low-frequency radio studies of galaxy groups, we also present a more detailed insight into four radio-emitting systems, for which the strength of the magnetic field inside their intergalactic medium (IGM) is calculated. The estimated values are comparable to that found inside star-forming galaxies, suggesting a dynamical and evolutionary importance of the magnetic field in galaxy groups., Comment: 4 figures, 4 tables and 15 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

38. The XXL Survey

Author

Paul Giles, Cathy Horellou, Stefano Ettori, Elias Koulouridis, C. Lidman, V. Smolvcic, Mark Birkinshaw, C. Adami, M. Bolzonella, S. Paltani, T. Sadibekova, Matt S. Owers, R. J. Tuffs, Florian Pacaud, L. Chiappetti, B. Garilli, L. Guennou, S. Maurogordato, Jochen Liske, Andrii Elyiv, Trevor J. Ponman, Meiert W. Grootes, A. Iovino, M. E. Ramos Ceja, Mauro Sereno, Michael J. I. Brown, Sean L. McGee, J. L. Willis, Bruno Altieri, I. Valtchanov, Andrew M. Hopkins, Ivan K. Baldry, Angela Bongiorno, S. Fotoupoulou, Aaron S. G. Robotham, Bianca M. Poggianti, V. Guglielmo, Cristian Vignali, Simon P. Driver, August E. Evrard, Fabio Gastaldello, Benedetta Vulcani, M. Plionis, Marco Scodeggio, Marguerite Pierre, University of St Andrews. School of Physics and Astronomy, Guglielmo, V., Poggianti, B.M., Vulcani, B., Adami, C., Gastaldello, F., Ettori, S., Fotoupoulou, S., Koulouridis, E., Ramos Ceja, M.E., Giles, P., McGee, S., Altieri, B., Baldry, I., Birkinshaw, M., Bolzonella, M., Bongiorno, A., Brown, M., Chiappetti, L., Driver, S., Elyiv, A., Evrard, A., Garilli, B., Grootes, M., Guennou, L., Hopkins, A., Horellou, C., Iovino, A., Lidman, C., Liske, J., Maurogordato, S., Owers, M., Pacaud, F., Paltani, S., Pierre, M., Plionis, M., Ponman, T., Robotham, A., Sadibekova, T., Scodeggio, M., Sereno, M., Smolčić, V., Tuffs, R., Valtchanov, I., Vignali, C., Willis, J., Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
luminosity function, mass function [Galaxies], Stellar mass, astro-ph.GA, FOS: Physical sciences, Astrophysics, clusters: general [Galaxies], 01 natural sciences, Virial theorem, galaxies: groups: general, 0103 physical sciences, QB Astronomy, Infrarot-Astrophysik - Abteilung Hinton, 010303 astronomy & astrophysics, QC, luminosity function [galaxies], QB, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 85A04, 010308 nuclear & particles physics, X-ray, DAS, Astronomy and Astrophysics, Virial mass, evolution [Galaxies], Astrophysics - Astrophysics of Galaxies, NATURAL SCIENCES. Physics, Redshift, Galaxy, PRIRODNE ZNANOSTI. Fizika, galaxies: luminosity function, groups: general [Galaxies], QC Physics, [SDU]Sciences of the Universe [physics], galaxies: clusters: general, mass function, Space and Planetary Science, Homogeneous, Astrophysics of Galaxies (astro-ph.GA), X-rays: galaxies: clusters, galaxies: luminosity function, mass function, galaxies: clusters [X-rays], Halo, galaxies: evolution
Abstract

The fraction of galaxies bound in groups in the nearby Universe is high (50% at z~0). Systematic studies of galaxy properties in groups are important in order to improve our understanding of the evolution of galaxies and of the physical phenomena occurring within this environment. We have built a complete spectrophotometric sample of galaxies within X-ray detected, optically spectroscopically confirmed groups and clusters (G&C), covering a wide range of halo masses at z, 20 pages, 18 figures, 6 tables, accepted for publication in A&A

Published
2018

39. The XXL Survey:VIII. MUSE characterization of intra cluster light in a z ~ 0.53 cluster of galaxies

Author

T. Sadibekova, S. Maurogordato, L. Guennou, Bianca M. Poggianti, Sean L. McGee, C. Adami, Nicolas Clerc, J. L. Willis, Marguerite Pierre, Emanuela Pompei, Cathy Horellou, Florian Pacaud, Mark Birkinshaw, and A. Iovino

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Cluster (physics), Astrophysics::Solar and Stellar Astrophysics, clusters: general [galaxies], Emission spectrum, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Redshift, Galaxy, Ram pressure, Stars, Supernova, Space and Planetary Science, clusters: intracluster medium [galaxies], Astrophysics of Galaxies (astro-ph.GA), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies. Gas hydrodynamical effects can additionally strip gas and dust from galaxies. The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. The present study is designed to characterise this ICL in a ~10^14 M_odot and z~0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse light. These sources were then spectroscopically characterised with MUSE. MUSE data were also used to compute redshifts of 24 cluster galaxies and search for cluster substructures. An atypically large amount of ICL has been detected in this cluster. Part of the detected diffuse light has a very weak optical stellar component and apparently consists mainly of gas emission, while other diffuse light sources are clearly dominated by old stars. Furthermore, emission lines were detected in several places of diffuse light. Our spectral analysis shows that this emission likely originates from low-excitation parameter gas. The stellar contribution to the ICL is about 2.3x10^9 yrs old even though the ICL is not currently forming a large number of stars. On the other hand, the contribution of the gas emission to the ICL in the optical is much greater than the stellar contribution in some regions, but the gas density is likely too low to form stars. These observations favour ram pressure stripping, turbulent viscous stripping, or supernovae winds as the origin of the large amount of intracluster light. Since the cluster appears not to be in a major merging phase, we conclude that ram pressure stripping is the most plausible process that generates the observed ICL sources., Accepted in A&A, english enhanced, figure location different than in the A&A version due to different style files, shortened abstract

Published
2016

40. The XXL Survey I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme

Author

David Rapetti, Bruno Altieri, Nicolas Clerc, N. Fourmanoit, R. Gastaud, Felipe Menanteau, Bianca M. Poggianti, Angela Bongiorno, M. E. Ramos-Ceja, Marcella Brusa, Andrii Elyiv, Stefano Ettori, Y. Dubois, S. Paltani, O. V. Melnyk, L. Guennou, Sean L. McGee, Emanuela Pompei, A. Butler, Dominique Eckert, C. Adami, F. Finet, C. De Breuck, V. Guglielmo, J. Delhaize, C. Schimd, A. Iovino, Cristian Vignali, K. Husband, Mauro Sereno, S. Desai, Arya Farahi, Steven L. Snowden, Cathy Horellou, Jean-Baptiste Melin, H. J. A. Röttgering, Vernesa Smolčić, Piero Ranalli, J. P. Le Fevre, Elias Koulouridis, J. L. Willis, A. Valotti, David N. Spergel, Minh Huynh, S. A. Stanford, I. Valtchanov, C. Lidman, Manolis Plionis, L. Chiappetti, Jean Surdej, M. Lieu, Thomas H. Reiprich, E. S. Rykoff, Daniel Pomarède, Florian Pacaud, Paolo Ciliegi, T. Sadibekova, I. Georgantopoulos, Sotiria Fotopoulou, C. Benoist, Julien Devriendt, F. Ziparo, S. Lavoie, Ian G. McCarthy, Jean Coupon, J. Démoclès, Mladen Novak, L. Faccioli, José Paulo Santos, Paul Giles, Adam Mantz, Malcolm N. Bremer, Graham P. Smith, Poshak Gandhi, Mark Birkinshaw, S. Maurogordato, Trevor J. Ponman, Ben J Maughan, Pier Stefano Corasaniti, August E. Evrard, Fabio Gastaldello, S. Raychaudury, A. M. C. Le Brun, Martin Kilbinger, J. L. Sauvageot, Sinan Aliş, Chieh-An Lin, E. Rozo, Patrick Valageas, Marguerite Pierre, Chiara Ferrari, B. Baran, Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), CEA/DCC/DRRV/SCD, Commissariat à l'Energie Atomique, Marcoule, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Herschel Science Centre, Agence Spatiale Européenne = European Space Agency (ESA), 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), College of Computing (GATECH), Georgia Institute of Technology [Atlanta], Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), INAF- Milano, Max-Planck-Institut für Extraterrestrische Physik (MPE), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), 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), Sub-department of Astrophysics [Oxford], Department of Physics [Oxford], University of Oxford-University of Oxford, 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), Université de Genève = University of Geneva (UNIGE), INAF-IASF Milano, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Département de Géologie, Université de Montréal (UdeM), Aristotle University of Thessaloniki, 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), Sr. PLM Consultant, Département d'Electronique, des Détecteurs et d'Informatique pour la Physique (ex SEDI) (DEDIP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institute for Space Applications and Remote Sensing (ISARS/NOA), National Observatory of Athens (NOA), Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], Université Quebec, Université du Québec à Chicoutimi (UQAC), AUTRES, Astronomical Observatory of Kiev, Taras Shevchenko National University of Kyiv, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), ISDC Data Centre for Astrophysics, INAF - Osservatorio Astronomico di Padova (OAPD), Lund Observatory, Lund University [Lund], Argelander Institute for Astronomy (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Leiden Observatory [Leiden], Universiteit Leiden, KIPAC, Stanford (KIPAC), Stanford University-SLAC National Accelerator Laboratory (SLAC), Stanford University, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), University of Reading (UOR), NASA Goddard Space Flight Center (GSFC), Service de Physique Théorique (SPhT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), European Space Agency (ESA), 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), Università di Bologna, Dipartimento di Astronomia, Università di Bologna [Bologna] (UNIBO), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), University of Oxford [Oxford]-University of Oxford [Oxford], École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), University of Geneva [Switzerland], Université de Montréal [Montréal], Département d'Electronique, des Détecteurs et d'Informatique (ex SEDI) (DEDI), National Observatory of Athens, Institute for Space Applications and Remote Sensing, Universiteit Leiden [Leiden], Stanford University [Stanford]-SLAC, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), 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), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), 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 de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), 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), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), 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), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), California Institute of Technology (CALTECH)-NASA, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Pierre, M., Pacaud, F., Adami, C., Alis, S., Altieri, B., Baran, N., Benoist, C., Birkinshaw, M., Bongiorno, A., Bremer, M.N., Brusa, M., Butler, A., Ciliegi, P., Chiappetti, L., Clerc, N., Corasaniti, P.S., Coupon, J., De Breuck, C., Democles, J., Desai, S., Delhaize, J., Devriendt, J., Dubois, Y., Eckert, D., Elyiv, A., Ettori, S., Evrard, A., Faccioli, L., Farahi, A., Ferrari, C., Finet, F., Fotopoulou, S., Fourmanoit, N., Gandhi, P., Gastaldello, F., Gastaud, R., Georgantopoulos, I., Giles, P., Guennou, L., Guglielmo, V., Horellou, C., Husband, K., Huynh, M., Iovino, A., Kilbinger, M., Koulouridis, E., Lavoie, S., Le Brun, A.M.C., Le Fevre, J.P., Lidman, C., Lieu, M., Lin, C.A., Mantz, A., Maughan, B.J., Maurogordato, S., Mccarthy, I.G., Mcgee, S., Melin, J.B., Melnyk, O., Menanteau, F., Novak, M., Paltani, S., Plionis, M., Poggianti, B.M., Pomarede, D., Pompei, E., Ponman, T.J., Ramos-Ceja, M.E., Ranalli, P., Rapetti, D., Raychaudury, S., Reiprich, T.H., Rottgering, H., Rozo, E., Rykoff, E., Sadibekova, T., Santos, J., Sauvageot, J.L., Schimd, C., Sereno, M., Smith, G.P., Smolčić, V., Snowden, S., Spergel, D., Stanford, S., Surdej, J., Valageas, P., Valotti, A., Valtchanov, I., Vignali, C., Willis, J., Ziparo, F., ITA, FRA, DEU, ESP, BEL, CAN, and TUR

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Large-scale structure of Universe, PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Table (information), X-rays: general, 01 natural sciences, X-rays, general, large-scale structure of Universe, galaxies, clusters, surveys, general [X-rays], 0103 physical sciences, Electronic form, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, Survey, 010303 astronomy & astrophysics, media_common, QB, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Photon statistics, 010308 nuclear & particles physics, Plan (archaeology), Astronomy and Astrophysics, Astronomy and Astrophysic, X-rays: galaxies: cluster, Galaxy, Pathfinder, Sky, Space and Planetary Science, X-rays: galaxies: clusters, Dark energy, galaxies: clusters [X-rays], Astrophysics - High Energy Astrophysical Phenomena, X-rays: diffuse background, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the XXL Survey, the largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The XXL Survey covers two extragalactic areas of 25 deg2 each at a point-source sensitivity of ~ 5E-15 erg/sec/cm2 in the [0.5-2] keV band (completeness limit). The survey's main goals are to provide constraints on the dark energy equation of state from the space-time distribution of clusters of galaxies and to serve as a pathfinder for future, wide-area X-ray missions. We review science objectives, including cluster studies, AGN evolution, and large-scale structure, that are being conducted with the support of approximately 30 follow-up programmes. We describe the 542 XMM observations along with the associated multi-lambda and numerical simulation programmes. We give a detailed account of the X-ray processing steps and describe innovative tools being developed for the cosmological analysis. The paper provides a thorough evaluation of the X-ray data, including quality controls, photon statistics, exposure and background maps, and sky coverage. Source catalogue construction and multi-lambda associations are briefly described. This material will be the basis for the calculation of the cluster and AGN selection functions, critical elements of the cosmological and science analyses. The XXL multi-lambda data set will have a unique lasting legacy value for cosmological and extragalactic studies and will serve as a calibration resource for future dark energy studies with clusters and other X-ray selected sources. With the present article, we release the XMM XXL photon and smoothed images along with the corresponding exposure maps. The XMM XXL observation list (Table B.1) is available in electronic form at the CDS. The present paper is the first in a series reporting results of the XXL-XMM survey., Comment: 17 pages, accepted in A&A

Published
2016

41. The XXL Survey II. The bright cluster sample: catalogue and luminosity function

Author

Dominique Eckert, Sophie Maurogordato, A. Iovino, L. Guennou, Sinan Aliş, C. Benoist, J. Démoclès, Daniel Pomarède, Jochen Liske, L. Faccioli, Ivan K. Baldry, J. P. Le Fevre, L. Chiappetti, Matt S. Owers, David Rapetti, N. Clerc, Florian Pacaud, Christopher Lidman, Trevor J. Ponman, Thomas H. Reiprich, Ivan Valtchanov, C. Adami, Patrick Valageas, Graham P. Smith, Marguerite Pierre, T. Sadibekova, Felipe Menanteau, Bianca M. Poggianti, F. Ardila, Cathy Horellou, Elias Koulouridis, F. Ziparo, Ben J Maughan, Mark Birkinshaw, M. Lieu, Bruno Altieri, V. Le Brun, Paul Giles, August E. Evrard, Fabio Gastaldello, Jon Willis, Richard J. Tuffs, E. Pompei, CEA/DCC/DRRV/SCD, Commissariat à l'Energie Atomique, Marcoule, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Max-Planck-Institut für Extraterrestrische Physik (MPE), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), 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), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Herschel Science Centre, European Space Agency (ESA), Joseph Louis LAGRANGE (LAGRANGE), 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, 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), INAF- Milano, Istituto Nazionale di Astrofisica (INAF), University of Geneva [Switzerland], INAF-IASF Milano, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], AUTRES, Institute for Space Applications and Remote Sensing (ISARS/NOA), National Observatory of Athens (NOA), Argelander Institute for Astronomy (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, University of Reading (UOR), Service de Physique Théorique (SPhT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), 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 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), National Observatory of Athens, Institute for Space Applications and Remote Sensing, Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Agence Spatiale Européenne = European Space Agency (ESA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), 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 Genève = University of Geneva (UNIGE), 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
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Infrarot-Astrophysik - Abteilung Hofmann, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Cosmology, surveys, 0103 physical sciences, Cluster (physics), cosmological parameters, 010303 astronomy & astrophysics, Galaxy cluster, QB, Luminosity function (astronomy), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Redshift, Space and Planetary Science, clusters: intracluster medium [galaxies], [SDU]Sciences of the Universe [physics], Cluster sampling, galaxies: clusters [X-rays], large-scale structure of Universe, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of $3\times 10^{-14}\,\mathrm{erg \,s^{-1}cm^{-2}}$ on the source flux within a 1$^{\prime}$ aperture. Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results. The bright cluster sample consists of systems with masses between $M_{500}=7\times 10^{13}$ and $3\times 10^{14} M_\odot$, mostly located between $z=0.1$ and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the predictions from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of $\sigma_8$ and/or $\Omega_m$ appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to $z\sim1$. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters., Comment: Accepted by A&A, 25 pages, 17 figures, 7 tables. The XXL-100-GC Master catalogue is available from the XXL Milan database (http://cosmosdb.iasf-milano.inaf.it/XXL/) and through the CDS (cdsarc.u-strasbg.fr)

Published
2016

42. The XXL Survey: IX. Optical overdensity and radio continuum analysis of a supercluster at $z=0.43$

Author

Stefano Ettori, Oskari Miettinen, Eva Schinnerer, Cathy Horellou, Elias Koulouridis, O. Melnyk, Vernesa Smolčić, Stephen Bourke, Florian Pacaud, Dinko Milaković, L. Chiappetti, Kunal Mooley, Chris Carilli, M. E. Ramos-Ceja, J. Delhaize, Mladen Novak, Marguerite Pierre, Fabio Gastaldello, N. Baran, Gregg Hallinan, and E. Pompei

Subjects
PRIRODNE ZNANOSTI. Fizika. Astronomija i astrofizika, 010504 meteorology & atmospheric sciences, Radio galaxy, media_common.quotation_subject, FOS: Physical sciences, Astrophysics, 01 natural sciences, Jansky, Supercluster, 0103 physical sciences, NATURAL SCIENCES. Physics. Astronomy and Astrophysics, clusters: general [galaxies], Continuum (set theory), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Photometric redshift, media_common, Physics, groups: general [galaxies], Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Galaxy, Redshift, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), catalogs, galaxies: clusters: general, galaxies: groups: general, radio continuum: galaxies
Abstract

We present observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward a sub-field of the XXL-North 25 deg2 field targeting the first supercluster discovered in the XXL Survey. The structure has been found at a spectroscopic redshift of 0.43 and extending over 0.̊35 × 0.̊1 on the sky. The aim of this paper is twofold. First, we present the 3 GHz VLA radio continuum observations, the final radio mosaic and radio source catalogue, and, second, we perform a detailed analysis of the supercluster in the optical and radio regimes using photometric redshifts from the CFHTLS survey and our new VLA-XXL data. Our final 3 GHz radio mosaic has a resolution of 3.̋2 × 1.̋9, and encompasses an area of 41' × 41' with rms noise level lower than ~ 20 μJy beam-1. The noise in the central 15' × 15' region is ≈ 11 μJy beam-1. From the mosaic we extract a catalogue of 155 radio sources with signal-to-noise ratio (S/N) ≥ 6, eight of which are large, multicomponent sources, and 123 (79%) of which can be associated with optical sources in the CFHTLS W1 catalogue. Applying Voronoi tessellation analysis (VTA) in the area around the X-ray identified supercluster using photometric redshifts from the CFHTLS survey we identify a total of seventeen overdensities at zphot = 0.35 - 0.50, 7 of which are associated with clusters detected in the XMM-Newton XXL data. We find a mean photometric redshift of 0.43 for our overdensities, consistent with the spectroscopic redshifts of the brightest cluster galaxies of seven X-ray detected clusters. The full VTA-identified structure extends over ~ 0.̊6 × 0.̊2 on the sky, which corresponds to a physical size of ~ 12 × 4 Mpc2 at z = 0.43. No large radio galaxies are present within the overdensities, and we associate eight (S/N> 7) radio sources with potential group/cluster member galaxies. The spatial distribution of the red and blue VTA-identified potential group member galaxies, selected by their observed g - r colours, suggests that the clusters are not virialised yet, but are dynamically young, as expected for hierarchical structure growth in a ΛCDM universe. Further spectroscopic data are required to analyse the dynamical state of the groups. The full catalogue is available as a queryable database table XXL_VLA_15 via the XXL Master Catalogue browser http://cosmosdb.iasf-milano.inaf.it/XXL. A copy of the catalogue and the mosaic are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?IX/49A FITS file of the reduced image is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A8

Published
2016

43. Mid-infrared dust in two nearby radio galaxies, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36)

Author

Hartmut Winkler, Cathy Horellou, B. Duah Asabere, Thomas H. Jarrett, Department of Astronomy, and Faculty of Science

Subjects
Brightness, Radio galaxy, Infrared, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, infrared: galaxies, 0103 physical sciences, galaxies: interactions, Astrophysics::Solar and Stellar Astrophysics, Spectroscopy, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Luminous infrared galaxy, 010308 nuclear & particles physics, galaxies: individual: NGC 612 (PKS 0131-36), Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), Galaxy, Space and Planetary Science, galaxies: individual: NGC 1316 (Fornax A), Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, galaxies: ISM
Abstract

Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron and Spitzer mid-infrared spectra. By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.6" to 5.5". Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 micron images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 micron images to estimate the stellar continuum contribution to the emission in the 12 and 22 micron bands. The two galaxies differ markedly in their mid-IR properties. The 3.4 micron brightness distribution can be well represented by the superposition of two Sersic models in NGC 1316 and by a Sersic model and an exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those of early-type galaxies; those of NGC 612 are in the range found for star-forming galaxies. From the 22 micron luminosity, we infer a star-formation rate of about 0.7 solar masses per year in NGC 1316 and about 7 solar masses per year in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 micron PAH line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images reveal resolved emission from dust in the central 1'-2' of the galaxies. (Abridged), Accepted for publication in A&A

Published
2016
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44. The XXL Survey: VI. The 1000 brightest X-ray point sources

Author

M. E. Ramos-Ceja, C. Adami, T. Sadibekova, Florian Pacaud, Dominique Eckert, Sophie Maurogordato, A. Iovino, L. Guennou, Matt S. Owers, Cathy Horellou, F. Ardila, Elias Koulouridis, Ivan K. Baldry, Christer Lidman, Andrii Elyiv, E. Pompei, Manolis Plionis, Stéphane Arnouts, Sinan Aliş, O. Melnyk, Marcella Brusa, Cristian Vignali, L. Faccioli, Sotiria Fotopoulou, Jon Willis, Seema Y Desai, Richard J. Tuffs, A. Stanford, Jochen Liske, Stéphane Paltani, Joseph J. Mohr, Malcolm N. Bremer, Angela Bongiorno, Marguerite Pierre, Enrico Piconcelli, Felipe Menanteau, Bianca M. Poggianti, L. Chiappetti, Piero Ranalli, Aristotle University of Thessaloniki, CEA/DCC/DRRV/SCD, Commissariat à l'Energie Atomique, Marcoule, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), ISDC Data Centre for Astrophysics, University of Geneva [Switzerland], Lund Observatory, Lund University [Lund], National Observatory of Athens, Institute for Space Applications and Remote Sensing, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), College of Computing (GATECH), Georgia Institute of Technology [Atlanta], Università di Bologna, Dipartimento di Astronomia, Università di Bologna [Bologna] (UNIBO), INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), INAF- Milano, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, AUTRES, Astronomical Observatory of Kiev, Taras Shevchenko National University of Kyiv, Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), INAF - Osservatorio Astronomico di Roma (OAR), Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), INAF-IASF Milano, Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], 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), 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), Excellence Cluster Universe, excellence cluster centre, Max-Planck-Institut für Extraterrestrische Physik (MPE), Ludwig-Maximilians-Universität München (LMU), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Fotopoulou, S., Pacaud, F., Paltani, S., Ranalli, P., Ramos-Ceja, M.E., Faccioli, L., Plionis, M., Adami, C., Bongiorno, A., Brusa, M., Chiappetti, L., Desai, S., Elyiv, A., Lidman, C., Melnyk, O., Pierre, M., Piconcelli, E., Vignali, C., Alis, S., Ardila, F., Arnouts, S., Baldry, I., Bremer, M., Eckert, D., Guennou, L., Horellou, C., Iovino, A., Koulouridis, E., Liske, J., Maurogordato, S., Menanteau, F., Mohr, J.J., Owers, M., Poggianti, B., Pompei, E., Sadibekova, T., Stanford, A., Tuffs, R., Willis, J., Université de Genève = University of Geneva (UNIGE), Institute for Space Applications and Remote Sensing (ISARS/NOA), National Observatory of Athens (NOA), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), 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 National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), 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 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
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Point source, Astrophysics::High Energy Astrophysical Phenomena, Infrarot-Astrophysik - Abteilung Hofmann, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Parameter space, catalogs, surveys, galaxies: active, X-rays: general, 01 natural sciences, Spectral line, Supercluster, general [X-rays], 0103 physical sciences, Survey, 010303 astronomy & astrophysics, Luminosity function, Astrophysics::Galaxy Astrophysics, QB, Photometric redshift, Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Galaxies: active, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, Redshift, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), active [galaxies], Catalog, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). The XXL Survey spans two fields of a combined 50 $deg^2$ observed for more than 6Ms with XMM-Newton, occupying the parameter space between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. This paper marks the first release of the XXL point source catalogue selected in the 2-10 keV energy band with limiting flux $F_{2-10keV}=4.8\cdot10^{-14}\rm{erg\,s^{-1}\,cm^{-2}}$. We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources and improved upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift model library. We also assign a probability to each source to be a star or an outlier. We model with Bayesian analysis the X-ray spectra assuming a power-law model with the presence of an absorbing medium. We find an average unabsorbed photon index of $\Gamma=1.85$ and average hydrogen column density $\log{N_{H}}=21.07 cm^{-2}$. We find no trend of $\Gamma$ or $N_H$ with redshift and a fraction of 26% absorbed sources ($\log N_{H}>22$). We show that the XXL-1000-AGN number counts extended the number counts of the COSMOS survey to higher fluxes and are fully consistent with the Euclidean expectation. We constrain the intrinsic luminosity function of AGN in the 2-10 keV energy band where the unabsorbed X-ray flux is estimated from the X-ray spectral fit up to z=3. Finally, we demonstrate the presence of a supercluster size structure at redshift 0.14, identified by means of percolation analysis of the XXL-1000-AGN sample. The XXL survey, reaching a medium flux limit and covering a wide area is a stepping stone between current deep fields and planned wide area surveys., Comment: 29 pages, 20 figures, 120 figures in the appendix, accepted for publication in A&A

Published
2016

45. Using rotation measure grids to detect cosmological magnetic fields: A Bayesian approach

Author

Keitaro Takahashi, H. Junklewitz, Marco Selig, V. Vacca, S. Ideguchi, Chiara Ferrari, Luigina Feretti, Niels Oppermann, Roberto Pizzo, Jens Jasche, Torsten A. Ensslin, Christopher A. Hales, Cathy Horellou, Martin Reinecke, Timothy W. Shimwell, M. Brueggen, Melanie Johnston-Hollitt, E. Carretti, M. Greiner, and Huub Roettgering

Subjects
Physics, COSMIC cancer database, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Magnetism, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, Redshift, Magnetic field, law.invention, Space and Planetary Science, law, 0103 physical sciences, Astronomical interferometer, Faraday cage, 010303 astronomy & astrophysics, Rotation (mathematics), Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Determining magnetic field properties in different environments of the cosmic large-scale structure as well as their evolution over redshift is a fundamental step toward uncovering the origin of cosmic magnetic fields. Radio observations permit the study of extragalactic magnetic fields via measurements of the Faraday depth of extragalactic radio sources. Our aim is to investigate how much different extragalactic environments contribute to the Faraday depth variance of these sources. We develop a Bayesian algorithm to distinguish statistically Faraday depth variance contributions intrinsic to the source from those due to the medium between the source and the observer. In our algorithm the Galactic foreground and the measurement noise are taken into account as the uncertainty correlations of the galactic model. Additionally, our algorithm allows for the investigation of possible redshift evolution of the extragalactic contribution. This work presents the derivation of the algorithm and tests performed on mock observations. With cosmic magnetism being one of the key science projects of the new generation of radio interferometers we have made predictions for the algorithm's performance on data from the next generation of radio interferometers. Applications to real data are left for future work., Comment: 27 pages, 14 figures, Submitted to A&A

Published
2016

46. Magnetic fields in ring galaxies

Author

E. A. Mikhailov, David Moss, Dmitry Sokoloff, Cathy Horellou, Rainer Beck, and Olga K. Sil'chenko

Subjects
Physics, Spiral galaxy, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astronomy and Astrophysics, Parity (physics), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Galaxy, Magnetic field, Interstellar medium, Space and Planetary Science, Excited state, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Disc, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Dynamo
Abstract

Many galaxies contain magnetic fields supported by galactic dynamo action. However, nothing definitive is known about magnetic fields in ring galaxies. Here we investigate large-scale magnetic fields in a previously unexplored context, namely ring galaxies, and concentrate our efforts on the structures that appear most promising for galactic dynamo action, i.e. outer star-forming rings in visually unbarred galaxies. We use tested methods for modelling $\alpha-\Omega$ galactic dynamos, taking into account the available observational information concerning ionized interstellar matter in ring galaxies. Our main result is that dynamo drivers in ring galaxies are strong enough to excite large-scale magnetic fields in the ring galaxies studied. The variety of dynamo driven magnetic configurations in ring galaxies obtained in our modelling is much richer than that found in classical spiral galaxies. In particular, various long-lived transients are possible. An especially interesting case is that of NGC 4513 where the ring counter-rotates with respect to the disc. Strong shear in the region between the disc and the ring is associated with unusually strong dynamo drivers for the counter-rotators. The effect of the strong drivers is found to be unexpectedly moderate. With counter-rotation in the disc, a generic model shows that a steady mixed parity magnetic configuration, unknown for classical spiral galaxies, may be excited, although we do not specifically model NGC 4513. We deduce that ring galaxies constitute a morphological class of galaxies in which identification of large-scale magnetic fields from observations of polarized radio emission, as well as dynamo modelling, may be possible. Such studies have the potential to throw additional light on the physical nature of rings, their lifetimes and evolution., Comment: 25 pages, 12 figures

Published
2016
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47. A plethora of diffuse steep spectrum radio sources in Abell 2034 revealed by LOFAR

Author

E. Retana-Montenegro, F. de Gasperin, Matt S. Owers, George Heald, Marijke Haverkorn, H. J. A. Röttgering, J. Sabater, Martin J. Hardcastle, Huib Intema, John McKean, S. S. Sridhar, Timothy W. Shimwell, Annalisa Bonafede, Cathy Horellou, Gianfranco Brunetti, Glenn J. White, R. J. van Weeren, Rossella Cassano, J. Luckin, Torsten A. Enßlin, Emanuela Orrú, D. N. Hoang, Philip Best, Marcus Brüggen, Wendy L. Williams, Roberto Pizzo, Krzysztof T. Chyzy, Leah K. Morabito, Andra Stroe, Chiara Ferrari, Matthias Hoeft, Shimwell, T.W., Luckin, J., Brüggen, M., Brunetti, G., Intema, H.T., Owers, M.S., Röttgering, H.J.A., Stroe, A., Van Weeren, R.J., Williams, W.L., Cassano, R., De Gasperin, F., Hoang, D.N., Hardcastle, M.J., Sridhar, S.S., Sabater, J., Best, P.N., Bonafede, A., Chyzy, K.T., Enßlin, T.A., Ferrari, C., Haverkorn, M., Hoeft, M., Horellou, C., McKean, J.P., Morabito, L.K., Orrù, E., Pizzo, R., Retana-Montenegro, E., White, G.J., Leiden University, University of Maryland [Baltimore County] (UMBC), University of Maryland System, Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Istituto di Radioastronomia [Bologna] (IRA), Istituto Nazionale di Astrofisica (INAF), National Radio Astronomy Observatory [Socorro] (NRAO), National Radio Astronomy Observatory (NRAO), Macquarie University, European Southern Observatory (ESO), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Netherlands Institute for Radio Astronomy (ASTRON), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], University of Hertfordshire [Hatfield] (UH), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, 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], Thüringer Landessternwarte Tautenburg (TLS), Chalmers University of Technology [Gothenburg, Sweden], Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], The Open University [Milton Keynes] (OU), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Astronomy, Harvard University [Cambridge]-Smithsonian Institution, 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), Radboud University [Nijmegen], and Ferrari, Chiara

Subjects
Radiation mechanisms: non-thermal, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Radio galaxy, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio continuum: general, [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Radio relics, Intracluster medium, radio continuum general, 0103 physical sciences, Abell 520, 010303 astronomy & astrophysics, Galaxy cluster, Astrophysics::Galaxy Astrophysics, acceleration of particles, Galaxies: clusters: Individual: abell 2034, [SDU.ASTR.CO] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, shock waves, Astronomy and Astrophysic, non-thermal [radiation mechanisms], Acceleration of particle, Galaxy, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Abell 2744, Radio halo, clusters: intracluster medium [galaxies], Shock wave, Space and Planetary Science, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, general [radio continuum], clusters: individual: Abell 2034 [galaxies], Astrophysics - High Energy Astrophysical Phenomena, Galaxies: clusters: intracluster medium
Abstract

With Low-Frequency Array (LOFAR) observations, we have discovered a diverse assembly of steep spectrum emission that is apparently associated with the intra cluster medium (ICM) of the merging galaxy cluster Abell 2034. Such a rich variety of complex emission associated with the ICM has been observed in few other clusters. This not only indicates that Abell 2034 is a more interesting and complex system than previously thought but it also demonstrates the importance of sensitive and high-resolution, low-frequency observations. These observations can reveal emission from relativistic particles which have been accelerated to sufficient energy to produce observable emission or have had their high energy maintained by mechanisms in the ICM. The most prominent feature in our maps is a bright bulb of emission connected to two steep spectrum filamentary structures, the longest of which extends perpendicular to the merger axis for 0.5Mpc across the south of the cluster. The origin of these objects is unclear, with no shock detected in the X-ray images and no obvious connection with cluster galaxies or AGNs. We also find that the X-ray bright region of the cluster coincides with a giant radio halo with an irregular morphology and a very steep spectrum. In addition, the cluster hosts up to three possible radio relics, which are misaligned with the cluster X-ray emission. Finally, we have identified multiple regions of emission with a very steep spectral index that seem to be associated with either tailed radio galaxies or a shock., 15 pages, 9 figures, 1 table, accepted for publication in MNRAS

Published
2016

48. A strong magnetic field in the jet base of a supermassive black hole

Author

Sebastien Muller, Susanne Aalto, Wouter Vlemmings, Ivan Marti-Vidal, and Cathy Horellou

Subjects
Active galactic nucleus, Event horizon, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Rotation, 7. Clean energy, symbols.namesake, Faraday effect, Astronomy, Astrophysics and Cosmology, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Jet (fluid), Supermassive black hole, Multidisciplinary, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), Magnetic field, 13. Climate action, Astrophysics of Galaxies (astro-ph.GA), symbols, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Active galactic nuclei (AGN) host some of the most energetic phenomena in the Universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama large mm/submm array (ALMA), we have detected a polarization signal (Faraday rotation) related to the strong magnetic field at the jet base of a distant AGN, PKS1830-211. The amount of Faraday rotation (rotation measure) is proportional to the magnetic field strength along the line of sight times the density of electrons. Although it is impossible to precisely infer the magnetic fields in the region of Faraday rotation, the high rotation measures derived suggest magnetic fields of at least tens of Gauss (and possibly considerably higher) on scales of the order of light days (0.01 pc) from the black hole., Comment: Published in Science, Volume 348, Issue 6232, pp. 311-314 (2015)

Published
2016
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49. LOFAR FACET CALIBRATION

Author

Chiara Ferrari, Craig L. Sarazin, Rossella Cassano, Ralph P. Kraft, Matthias Hoeft, George Heald, R. Pizzo, Gianfranco Brunetti, Lawrence Rudnick, J. Sabater, Laura Birzan, S. S. Murray, William A. Dawson, Huub Röttgering, Glenn J. White, Aurora Simionescu, George K. Miley, Huib Intema, Andra Stroe, Matt J. Jarvis, D. A. Rafferty, Felipe Andrade-Santos, Philip Best, Cathy Horellou, F. de Gasperin, R. J. van Weeren, Krzysztof T. Chyzy, M. Mevius, Wendy L. Williams, Judith H. Croston, Martin J. Hardcastle, Marcus Brüggen, S. S. Sridhar, William R. Forman, S. van der Tol, T. J. Dijkema, Timothy W. Shimwell, Georgiana A. Ogrean, Annalisa Bonafede, Torsten A. Ensslin, Emanuela Orru, Christine Jones, Ferrari, Chiara, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Leiden University, Netherlands Institute for Radio Astronomy (ASTRON), University of Hertfordshire [Hatfield] (UH), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Istituto di Radioastronomia [Bologna] (IRA), Istituto Nazionale di Astrofisica (INAF), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Lawrence Livermore National Laboratory (LLNL), University of Minnesota [MN, USA], University of Virginia, Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), University of Southampton, Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, 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), Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), Thüringer Landessternwarte Tautenburg (TLS), Chalmers University of Technology [Gothenburg, Sweden], Oxford Astrophysics, University of Oxford, University of the Western Cape, National Radio Astronomy Observatory [Socorro] (NRAO), National Radio Astronomy Observatory (NRAO), Johns Hopkins University (JHU), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), The Open University [Milton Keynes] (OU), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Astronomy, Smithsonian Institution-Harvard University [Cambridge], University of Virginia [Charlottesville], 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), University of Oxford [Oxford], Weeren, R. J. Van, Williams, W.L., Hardcastle, M.J., Shimwell, T.W., Rafferty, D.A., Sabater, J., Heald, G., Sridhar, S.S., Dijkema, T.J., Brunetti, G., Brüggen, M., Andrade-Santos, F., Ogrean, G.A., Röttgering, H.J.A., Dawson, W.A., Forman, W.R., Gasperin, F. De, Jones, C., Miley, G.K., Rudnick, L., Sarazin, C.L., Bonafede, A., Best, P.N., Birzan, L., Cassano, R., Chyzy, K.T., Croston, J.H., Ensslin, T., Ferrari, C., Hoeft, M., Horellou, C., Jarvis, M.J., Kraft, R.P., Mevius, M., Intema, H.T., Murray, S.S., Orrú, E., Pizzo, R., Simionescu, A., Stroe, A., Tol, S. Van Der, and White, G.J.

Subjects
Facet (geometry), Computer science, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], media_common.quotation_subject, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, FOS: Physical sciences, Field of view, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio telescope, [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 0103 physical sciences, Calibration, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, Remote sensing, [SDU.ASTR.CO] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, technique, Astronomy and Astrophysic, interferometric [techniques], [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Space and Planetary Science, Sky, techniques: interferometric, interferometric, Ionosphere, Antenna (radio), Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

著者人数: 42名, Accepted: 2016-01-18, 資料番号: SA1160093000

Published
2016

50. Faraday tomography of the local interstellar medium with LOFAR: Galactic foregrounds towards IC342

Author

Charlotte Sobey, Anna M. M. Scaife, M. I. R. Alves, Vibor Jelić, M. Iacobelli, Cathy Horellou, D. D. Mulcahy, Torsten A. Enßlin, H. J. A. Röttgering, Ivan Marti-Vidal, D. H. F. M. Schnitzeler, W. Reich, Ron Beck, George Heald, A. G. de Bruyn, A. Horneffer, M. Haverkorn, S. S. Sridhar, Jamie Farnes, K. Ferrière, C. L. Van Eck, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Astronomy

Subjects
Astronomy, DUST, Astrophysics, 01 natural sciences, ISM: clouds, law.invention, MHZ, law, Polarization, DEPOLARIZATION, Faraday cage, 010303 astronomy & astrophysics, Physics, Line-of-sight, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], ISM: magnetic fields, polarization, local insterstellar matter, radio continuum: ISM, Magnetic field, WIDE-FIELD, symbols, clouds [ISM], RADIO-SOURCES, Local insterstellar matter, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Radio telescope, symbols.namesake, 0103 physical sciences, Faraday effect, BUBBLE, Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, magnetic fields [ISM], Astronomy and Astrophysics, LOFAR, ISM [Radio continuum], Astrophysics - Astrophysics of Galaxies, Galaxy, Interstellar medium, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), TELESCOPES, EMISSION, SKY SURVEY, ROTATION MEASURE SYNTHESIS
Abstract

The new generation of low-frequency radio telescopes, such as the Low Frequency Array (LOFAR: a Square Kilometre Array-low pathfinder), provides advancements in our capability of probing Galactic magnetism through low-frequency polarimetry. Maps of diffuse polarized radio emission and Faraday rotation can be used to infer properties of, and trace structure in, the magnetic fields in the ISM. However, to date very little of the sky has been probed at high angular and Faraday depth resolution. We observed a 5x5 degree region centred on the nearby galaxy IC342 using LOFAR in the frequency range 115-178 MHz at 4 arcmin resolution and performed Faraday tomography to detect foreground Galactic polarized synchrotron emission separated by Faraday depth (different amounts of Faraday rotation). Our Faraday depth cube shows rich polarized structure, with up to 30 K of polarized emission at 150 MHz. We detect two overlapping diffuse polarized features that are clearly separated in Faraday depth. Faraday-thick structures at such low frequencies would be too strongly depolarized to explain the observations and are therefore rejected. Only Faraday thin structures will not be strongly depolarized; producing such structures requires localized variations in the ratio of synchrotron emissivity to Faraday depth per unit distance, which can arise from several physical phenomena, such as a transition between regions of ionized and neutral gas. We conclude that the observed polarized emission is Faraday thin, and propose that the emission originates from two neutral clouds in the local ISM. We have modeled the Faraday rotation for this line of sight and estimated that the line of sight component of magnetic field of the local ISM for this direction varies between -0.86 and +0.12 uG. We propose that this may be a useful method for mapping magnetic fields within the local ISM., Comment: 17 pages, 12 figures, accepted for publication in A&A

Published
2016
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