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SPT-CL J2106-5844 is among the most massive galaxy clusters at z>1 yet
discovered. Recent studies indicate SPT-CL J2106-5844 is undergoing a
major merger, and efforts are underway to better characterise the
system. Di Mascolo et al. have used ALMA, ACA and Chandra data to
study the intracluster medium in this system. These measurements are
coupled with radio observations from the ASKAP EMU pilot survey and
the ATCA to search for diffuse non-thermal emission. The ASKAP and
ATCA data are processed and imaged to specifically highlight any
potential diffuse radio emission. The EMU radio observations reveal a
diffuse radio structure ~400 kpc in projected extent along the
north-west/south-east direction, indicative of strong activity from
the active galactic nucleus within the brightest cluster galaxy. The
image above shows a composite Hubble Space Telescope image with
contours from the EMU (dashed yellow) and 2.1 GHz ATCA (solid white)
images. The corresponding synthesized beams are shown in the bottom
right corner following the same color convention. The outskirts of
the extended structure observed in the EMU image are found to be
contaminated by point-like sources. Among the
most prominent features is the southernmost component in the EMU map,
though, with no redshift identification, we cannot rule out the
possibility that it is not associated with the cluster itself. This
feature (labelled C1) coincides with a compact emission in the ATCA
data, and has an optical counterpart in the Hubble Space Telescope
(HST) image. A second source (C2) is identified in the ATCA image and
found to be surrounded by a combination of diffuse emission and a
blend of multiple compact sources. If associated with the central
radio galaxy, these may correspond to knot-like features in one arm of
the radio jet. On the other hand, the radio emission from C2 may be
related to a separate radio galaxy, although with the current
resolution it is difficult to determine its optical counterpart. The
southern diffuse emission (C3) detected midway between the BCG and the
compact source C1 appears cospatial with a collection of elliptical
galaxies identified in the HST image and it is not yet possible to
determine whether the radio emission is generated in its entirety by
the dominant AGN or by a complex of radio-loud sources. More details
are give in
the preprint of the paper.
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