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14th of August 2020
Radio relics in a galaxy cluster
Duchesne et al. present a radio and X-ray analysis of the galaxy cluster SPT-CL J2032−5627. Data from the Australian Square Kilometre Array Pathfinder (ASKAP) at 943 MHz shows two previously undetected radio relics at either side of the cluster. Archival data from Australia Telescope Compact Array (ATCA) data at 5.5 GHz is used in conjunction with the new ASKAP data to determine that both have steep integrated radio spectra. No shock is seen in XMM-Newton observations, however, the southeast relic is preceded by a cold front in the X-ray–emitting intra-cluster medium. The excellent low-surface brightness sensitivity of ASKAP and the ATCA provide the ability to find heretofore undetected diffuse sources, suggesting these low-power radio relics will become more prevalent in upcoming large-area radio surveys such as the Evolutionary Map of the Universe (EMU).

The image above shows the galaxy cluster. The background optical image is from Dark Energy Survey Data Release 1. The ASKAP source-subtracted data (i.e., after compact sources are removed) are shown in magenta overlaid with XMM-Newton data in blue. More details are given in the preprint of the paper, which will be published in Publications of the Astronomical Society of Australia.

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