The peculiar cluster MACS J0417.5-1154 in the C and X-bands

TL;DR

This study uses multi-frequency radio observations to analyze the diffuse emission in the massive galaxy cluster MACS J0417.5-1154, revealing insights into radio halos and merger energetics.

Contribution

It provides a detailed multi-frequency analysis of diffuse radio emission in MACS J0417.5-1154, clarifying previous low-frequency emission estimates and emphasizing the importance of high-frequency data.

Findings

Diffuse emission estimates at 5.5 and 9.0 GHz from ATCA.

Reassessment of low-frequency diffuse emission, correcting earlier underestimates.

High-frequency observations help understand radio halos and cluster merger energetics.

Abstract

We present 5.5 and 9.0 GHz Australia Telescope Compact Array (ATCA) observations of the cluster MACSJ0417.5-1154, one of the most massive galaxy clusters and one of the brightest in X-ray in the Massive Cluster Survey (MACS). We estimate diffuse emission at 5.5 and 9.0 GHz from our ATCA observations, and compare the results with the 235 MHz and 610 MHz GMRT observations and 1575 MHz VLA observations. We also estimate the diffuse emission at low frequencies from existing GLEAM survey data (using the MWA telescope), and find that the steepening reported in earlier studies may have been an artefact of underestimates of diffuse emission at low frequencies. High-frequency radio observations of galaxy cluster mergers therefore provide an important complement to low-frequency observations, not only for a probing the `on' and `off' state of radio halos in these mergers, but also to constrain energetics of cluster mergers. We comment on the future directions that further studies of this cluster can take.