Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z = 0.306), which reveal the presence of a shock front 1.5 Mpc east of the cluster core. The surface-brightness jump coincides with the position of a known radio relic. Although the surface-brightness jump indicates a weak shock with a Mach number M=1.7-0.3+0.5, the plasma in the post-shock region has been heated to a very high temperature (~13 keV) by the passage of the shock wave. The low-acceleration efficiency expected from such a weak shock suggests that mildly relativistic electrons have been re-accelerated by the passage of the shock front.
Eckert, D., Jauzac, M., Vazza, F., Owers, M.S., Kneib, J.-., Tchernin, C., et al. (2016). A shock front at the radio relic of Abell 2744. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 461(2), 1302-1307 [10.1093/mnras/stw1435].
A shock front at the radio relic of Abell 2744
Eckert, D.
;Vazza, F.Investigation
;
2016
Abstract
Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z = 0.306), which reveal the presence of a shock front 1.5 Mpc east of the cluster core. The surface-brightness jump coincides with the position of a known radio relic. Although the surface-brightness jump indicates a weak shock with a Mach number M=1.7-0.3+0.5, the plasma in the post-shock region has been heated to a very high temperature (~13 keV) by the passage of the shock wave. The low-acceleration efficiency expected from such a weak shock suggests that mildly relativistic electrons have been re-accelerated by the passage of the shock front.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
