Extended X-ray emission from non-thermal sources in the COSMOS field: a detailed study of a large radio galaxy at z = 1.168

Scientific paper - Original scientific paper

• Author: Vibor Jelić
• Author: Vernesa Smolčić
• Author: Alexis Finoguenov
• Author: Masayuki Tanaka
• Author: Francesca Civano
• Author: Eva Schinnerer
• Author: Nico Cappelluti
• Author: Anton Koekemoer
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

X-ray selected galaxy group samples are usually generated by searching for extended X-ray sources that reflect the thermal radiation of the intragroup medium. On the other hand, large radio galaxies that regularly occupy galaxy groups also emit in the X-ray window, and their contribution to X-ray selected group samples is still not well understood. In order to investigate their relative importance, we have carried out a systematic search for non-thermal extended X-ray sources in the Cosmic Evolution Survey (COSMOS) field. Based on the morphological coincidence of X-ray and radio extensions, out of 60 radio galaxies, and ∼300 extended X-ray sources, we find only one candidate where the observed extended X-ray emission arises from non-thermal processes related to radio galaxies. We present a detailed analysis of this source, and its environment. Our results yield that external inverse Compton emission of the lobes is the dominant process that generates the observed X-ray emission of our extended X-ray candidate, with a minor contribution from the gas of the galaxy group hosting the radio galaxy. Finally, we show that finding only one potential candidate in the COSMOS field (in a redshift range 0 < z < 6 and with radio luminosity between 1025 and 1030 W Hz−1) is consistent with expected X-ray counts arising from synchrotron lobes. This implies that these sources are not a prominent source of contamination in samples of X-ray selected clusters/groups, but they could potentially dominate the z > 1 cluster counts at the bright end (SX > 7 × 10−15 erg s−1 cm2).

• Keywords (english): radiation mechanisms: non-thermal; radiation mechanisms: thermal; surveys; galaxies: active; radio continuum: galaxies; X-rays: galaxies: clusters
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Monthly Notices of the Royal Astronomical Society
• Numbering: vol. 423, no. 3, pp. 2753-2763
• p-ISSN: 0035-8711
• e-ISSN: 1365-2966
• DOI: https://doi.org/10.1111/j.1365-2966.2012.21085.x
• URN:NBN: urn:nbn:hr:217:305057
• Publication: 2012
• Document URL: https://academic.oup.com/mnras/article/423/3/2753/2460821
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2012 April 10. Received 2012 April 10; in original form 2011 August 8. Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided.
• Created on: 2019-11-15 18:37:28