How many radio relics await discovery?
Entity
UAM. Departamento de Física TeóricaPublisher
Oxford University Press; Royal Astronomical SocietyDate
2012-03-01Citation
10.1111/j.1365-2966.2011.20118.x
Monthly Notices of the Royal Astronomical Society 420.3 (2012): 2006-2019
ISSN
0035-8711 (print); 1365-2966 (online)DOI
10.1111/j.1365-2966.2011.20118.xFunded by
SEN acknowledges support by the Deutsche Forschungsgemeinschaft under the grant MU1020 16-1. MH cknowledges support by the research group FOR 1254 ‘Magnetisation of Interstellar and Intergalactic Media: The Prospects of Low-Frequency Radio Observations’ founded by the Deutsche Forschungsgemeinschaft. GY acknowledges the support of MICINN (Spain) through research grants FPA2009- 08958, AYA2009-13875-C03-02 and CONSOLIDER-INGENIO SyEC (CSD2007.0050). He also thanks Comunidad de Madrid for partial support under the ASTROMADRID project (CAM S2009/ESP-1496)Project
Comunidad de Madrid. S2009/ESP-1496/ ASTROMADRIDEditor's Version
http://dx.doi.org/10.1111/j.1365-2966.2011.20118.xSubjects
Galaxies: clusters: general; Large-scale structure of Universe; Methods: numerical; Radiation mechanisms: non-thermal; Shock waves; FísicaNote
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2012 RAS © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedRights
© 2012 The Authors; © 2012 RASAbstract
Upcoming radio telescopes will allow us to study the radio sky at low frequencies with unprecedented sensitivity and resolution. New surveys are expected to discover a large number of new radio sources, in particular those with a steep radio spectrum. Here we investigate the abundance of radio relics, i.e. steep-spectrum diffuse radio emission coming from the periphery of galaxy clusters, which is believed to trace shock waves induced by cluster mergers. With the advent of comprehensive relic samples, a framework is needed to analyse the relic abundance statistically. To this end, we introduce the probability of finding a relic located in a galaxy cluster with given mass and redshift, which allows us to relate the halo mass function of the Universe to radio-relic number counts. To date, about 45 relics have been reported in the literature and we compile the resulting counts, N(>S1.4). In principle, the parameters of the distribution could be determined using a sufficiently large relic sample. However, since the number of known relics is still small, for that purpose we use the MareNostrum Universe simulation to determine the relic radio-power scaling with cluster mass and redshift. Our model is able to reproduce the recently found tentative evidence for an increase in the fraction of clusters hosting relics, both with X-ray luminosity and redshift, using an X-ray flux-limited cluster sample. Moreover, we find that a considerable fraction of faint relics (S1.4≲ 10 mJy) reside in clusters with an X-ray flux below ≲ 3 × 10-12 erg s-1 cm-2. Finally, we estimate the number of radio relics that await discovery by future low-frequency surveys proposed for the Low Frequency Array (LOFAR) and the Westerbork Synthesis Radio Telescope (WSRT). We estimate that the Westerbork Observations of the Deep APERTIF Northern-Sky (WODAN) survey proposed for WSRT may discover 900 relics and that the LOFAR-Tier 1-120MHz survey may discover about 2500 relics. However, the actual number of newly discovered relics will depend crucially on the existence of sufficiently complete galaxy cluster catalogues
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Google Scholar:Nuza, Sebastián E.
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Hoeft, M.
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van Weeren, R. J.
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Gottlöber, S.
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Yepes Alonso, Gustavo
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