Suzaku X-ray study of the double radio relic galaxy cluster CIZA J2242.8+5301

Akamatsu, H. and van Weeren, R. J. and Ogrean, G. A. and Kawahara, H. and Stroe, A. and Sobral, D. and Hoeft, M. and Rottgering, H. and Brueggen, M. and Kaastra, J. S. (2015) Suzaku X-ray study of the double radio relic galaxy cluster CIZA J2242.8+5301. Astronomy and Astrophysics, 582. ISSN 1432-0746

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Abstract

Context. We present the results from Suzaku observations of the merging cluster of galaxies CIZA J2242.8+5301 at z = 0.192. Aims. To study the physics of gas heating and particle acceleration in cluster mergers, we investigated the X-ray emission from CIZAJ2242.8+5301, which hosts two giant radio relics in the northern and southern part of the cluster. Methods. We analyzed data from three-pointed Suzaku observations of CIZA J2242.8+5301 to derive the temperature distribution in four different directions. Results. The intracluster medium (ICM) temperature shows a remarkable drop from 8.5(-0).(+0.8)(6) keV to 2.7(-0.4)(+0.7) keV across the northern radio relic. The temperature drop is consistent with a Mach number M-n = 2.7(-0.4)(+0.7) and a shock velocity v(shock:n) = 2300(-400)(+700) km s(-1). We also confirm the temperature drop across the southern radio relic. However, the ICM temperature beyond this relic is much higher than beyond the northern relic, which gives a Mach number M-s = 1.7(-0.3)(+0.4) and shock velocity v(shock:s) = 2040(-410)(+550) km s(-1). These results agree with other systems showing a relationship between the radio relics and shock fronts which are induced by merging activity. We compare the X-ray derived Mach numbers with the radio derived Mach numbers from the radio spectral index under the assumption of diffusive shock acceleration in the linear test particle regime. For the northern radio relic, the Mach numbers derived from X-ray and radio observations agree with each other. Based on the shock velocities, we estimate that CIZA J2242.8+5301 is observed approximately 0.6 Gyr after core passage. The magnetic field pressure at the northern relic is estimated to be 9% of the thermal pressure.

Item Type: Journal Article
Journal or Publication Title: Astronomy and Astrophysics
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 77523
Deposited By: ep_importer_pure
Deposited On: 20 Jan 2016 11:52
Refereed?: Yes
Published?: Published
Last Modified: 17 Feb 2020 02:46
URI: https://eprints.lancs.ac.uk/id/eprint/77523

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