Chandra and XMM-Newton observations of A2256: cold fronts, merger shocks, and constraint on the IC emission

Journal
Date Issued
2020
Author(s)
Ge, Chong
•
Liu, Ruo-Yu
•
Sun, Ming
•
Yu, Heng
•
Rudnick, Lawrence
•
Eilek, Jean
•
Owen, Frazer
•
Dasadia, Sarthak
•
•
Markevitch, Maxim
•
Clarke, Tracy E.
•
Jones, Thomas W.
•
•
•
Finoguenov, Alexis
•
Eckert, Dominique
DOI
Abstract
We present the results of deep Chandra and XMM-Newton observations of a complex merging galaxy cluster Abell 2256 (A2256) that hosts a spectacular radio relic (RR). The temperature and metallicity maps show clear evidence of a merger between the western subcluster (SC) and the primary cluster (PC). We detect five X-ray surface brightness edges. Three of them near the cluster centre are cold fronts (CFs): CF1 is associated with the infalling SC; CF2 is located in the east of the PC; and CF3 is located to the west of the PC core. The other two edges at cluster outskirts are shock fronts (SFs): SF1 near the RR in the NW has Mach numbers derived from the temperature and the density jumps, respectively, of MT = 1.62 ± 0.12 and Mρ = 1.23 ± 0.06; SF2 in the SE has MT = 1.54 ± 0.05 and Mρ = 1.16 ± 0.13. In the region of the RR, there is no evidence for the correlation between X-ray and radio substructures, from which we estimate an upper limit for the inverse-Compton emission, and therefore set a lower limit on the magnetic field (˜ 450 kpc from PC centre) of B > 1.0 μG for a single power-law electron spectrum or B > 0.4 μG for a broken power-law electron spectrum. We propose a merger scenario including a PC, an SC, and a group. Our merger scenario accounts for the X-ray edges, diffuse radio features, and galaxy kinematics, as well as projection effects.
Volume
497
Issue
4
Start page
4704
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2020MNRAS.497.4704G
Rights
open.access
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