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Clusters of galaxies are the most massive gravitationally bound
objects in the universe. These clusters grow through collisions and
mergers, which result in cluster-wide magnetic fields, generating
radio halos via synchrotron radiation. Galaxy clusters can be bright
X-ray sources, with the X-ray emission revealing the thermal component
of the gas in the cluster.
MACS J0417.5-1154, discovered in the Massive Cluster Survey, is a hot,
massive cluster. It was initially detected at low radio frequencies,
235 MHz, 610 MHz, and 1575 MHz, prompting Sandhu et al. to extend
these studies to higher frequencies with the Australia Telescope
Compact Array.
The image above shows a natural-weighted image of the entire region of
the MACS J0417-1154 at 5.5 GHz, made with the inner five antennas
in the H168 array configuration. The synthesized beam, 46 arcseconds by
32 arcseconds is shown in the bottom left-hand corner. Contours start
at 5x the rms noise level of 8 μJy/beam. After removing the
contributions from the bright point sources near the centre of the
cluster, the diffuse emission can be measured. The level of diffuse
emission at 5.5 and 9 GHz is consistent with an extrapolation from 610
MHz and 1575 MHz.
The results are published in
"The peculiar cluster MACS J0417.5-1154 in the C and X-bands"
in Astrophysics and Space Science.
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