SHOCK HEATING OF THE MERGING GALAXY CLUSTER A521
- Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', via della Ricerca Scientifica, 1, I-00133 Roma (Italy)
- NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)
- Joint Space-Science Institute, University of Maryland, College Park, MD 20742-2421 (United States)
A521 is an interacting galaxy cluster located at z = 0.247, hosting a low-frequency radio halo connected to an eastern radio relic. Previous Chandra observations hinted at the presence of an X-ray brightness edge at the position of the relic, which may be a shock front. We analyze a deep observation of A521 recently performed with XMM-Newton in order to probe the cluster structure up to the outermost regions covered by the radio emission. The cluster atmosphere exhibits various brightness and temperature anisotropies. In particular, two cluster cores appear to be separated by two cold fronts. We find two shock fronts, one that was suggested by Chandra and that is propagating to the east, and another to the southwestern cluster outskirt. The two main interacting clusters appear to be separated by a shock-heated region, which exhibits a spatial correlation with the radio halo. The outer edge of the radio relic coincides spatially with a shock front, suggesting that this shock is responsible for the generation of cosmic-ray electrons in the relic. The propagation direction and Mach number of the shock front derived from the gas density jump, M = 2.4 {+-} 0.2, are consistent with expectations from the radio spectral index, under the assumption of Fermi I acceleration mechanism.
- OSTI ID:
- 22167774
- Journal Information:
- Astrophysical Journal, Vol. 764, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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