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10th of October 2023
ASKAP and eROSITA surveys of galaxy clusters
by Böckmann et al.
The extended ROentgen Survey with an Imaging Telescope Array (eROSITA) telescope on board the Spectrum-RoentgenGamma (SRG) mission has completed the first eROSITA All-Sky Survey (eRASS:1), detecting ∼104 galaxy clusters at X-ray energies in the western Galactic hemisphere. At radio wavelengths, ASKAP Pilot Survey observations for the EMU team detected 220,000 sources in a 270 square degree field overlapping with eRASS:1. Böckmann et al. have used these two surveys to study radio-mode active galactic nuclei in clusters. In order to understand the efficiency of radio-mode feedback at the centers of galaxy clusters, the team have related the radio properties of the brightest cluster galaxies to the X-ray properties of the host clusters, finding a statistically significant correlation between the X-ray luminosity of the cluster and the 944 MHz radio luminosity of the corresponding central radio galaxy. There is also a positive trend between the radio power and the largest linear size of the radio source. They find an anticorrelation between the central cooling time and the radio luminosity, indicating a need for more powerful active galactic nuclei in clusters with short central cooling times.

The image above shows radio cutout from the EMU image of cluster J201832.9-524656 (Abell S0861) at a redshift of z = 0.05 showing two elongated radio sources. The optical overlay reveals a complex interplay between at least three radio galaxies on the northern radio source and an infalling radio galaxy in the southern source.

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