Large-scale Radio Sources in Dynamically Disturbed Clusters
A 3.5 Mpc-long radio relic in the galaxy cluster ClG 0217+70
We present new observations of the galaxy cluster clg0217+70.5 from the large area telescope (lofar) at 141 mhz and the very large array (vla) at 1.5 ghz.
The new data confirm the presence of a giant radio halo in the cluster centre and multiple radio relics in the outskirts.
The radio and x-ray emission from the halo are positively correlated, implying a tight relation between the thermal and non-thermal components of the gas in the cluster centre.
The se radio structure with a projected size of 3.5 mpc is the most extended radio relic detected to date.
The spectral index across the width of the relics steepens towards the cluster centre, suggesting the energy ageing in the post-shock regions.
This discrepancy could be because the relation between injection and integrated spectral indices does not hold for distant shocks, suggesting that the cooling time for the radio-emitting electrons is shorter than the crossing time of the shocks.
The variations in the surface brightness of the relics and the low shock mach numbers suggest that the radio-emitting electrons are re-accelerated from fossil gas that is originally energised by active galactic nucleus activities.
D. N. Hoang, X. Zhang, C. Stuardi, T. W. Shimwell, A. Bonafede, M. Brüggen, G. Brunetti, A. Botteon, R. Cassano, F. de Gasperin, G. Di Gennaro, H. Intema, K. Rajpurohit, H. J. A. Röttgering, A. Simionescu, R. J. van Weeren