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9th of February 2022
Radio footprints of a minor merger in the Shapley Supercluster
by Venturi et al.
The Shapley Supercluster is one of the richest and most massive concentrations of gravitationally bound galaxy clusters in the local Universe. It is located in the southern sky and lies behind the Hydra-Centaurus cluster. Overall, the structure covers a redshift range from 0.033 to 0.06. Due to the very high overdensity and large number of galaxy clusters, and its relative proximity, it is an ideal place to start investigating the effects of group accretion and cluster minor mergers. Venturi et al. have used ASKAP, the GMRT and MeerKAT radio telescopes to investigate the less energetic events of mass assembly in the Shapley Supercluster from supercluster down to galactic scales. They report the first GHz frequency detection of extremely low brightness intercluster diffuse emission on a ∼ 1 Mpc scale connecting the Abell 3562 cluster and the galaxy group SC 1329–313, which is morphologically similar to the X-ray emission in the region. Their study strongly supports the scenario of a flyby of SC 1329–313 north of A 3562 into the supercluster core.

The figure above is a grey-scale image of the full field imaged by ASKAP at 887 MHz. The noise level ranges between 30 and 50 µJy/beam across the field. The radio galaxy PKS 1333–33 (which is part of the foreground Hydra-Centaurus cluster) is clearly visible in the bottom–left part of the field. Messier 83, a foreground massive barred spiral galaxy, is also visible in the top-left part of the field. The black contours show the number density of the galaxies at the redshift of the Shapley Supercluster. The contours correspond to 5, 10, 20, 40, 80, 160 galaxies per square megaparsec. The region studed by Venturi et al., from A 3562 to the central part of A 3558 (east to west) is highlighted by the red rectangle. The green and purple circles show the GMRT (Giant Metre-wave Radio Telescope) pointings, and the full area covered by the primary beam. The paper will be published in Astronomy & Astrophysics.

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