| Summary: | The goal of this study is to extend our current knowledge of the diffuse radio source (halo
and relic) populations to z > 0.3. Here, we report GMRT and EVLA radio observations
of six galaxy clusters taken from the MAssive Cluster Survey (MACS) catalogue to detect
diffuse radio emission. We used archival GMRT (150, 235, and 610 MHz) and EVLA (L
band) data and made images at multiple radio frequencies of the following six clusters –
MACSJ0417.5−1154, MACSJ1131.8−1955, MACSJ0308.9+2645, MACSJ2243.3−0935,
MACSJ2228.5+2036, and MACSJ0358.8−2955. We detect diffuse radio emission (halo or
relic, or both) in the first four clusters. In the last two clusters, we do not detect any diffuse radio
emission but we put stringent upper limits on their radio powers. We also use archival Chandra
X-ray data to carry out morphology and substructure analysis of these clusters. We find that
based on X-ray data, these MACS clusters are non-relaxed and show substructures in their
temperature distribution. The radio powers of the first four MACS clusters are consistent with
their expected values in the LX–P1.4 GHz plot. However, we found ultrasteep spectrum radio
halo in the MACSJ0417.5−1154 cluster whose rest-frame cut-off frequency is at ∼900 MHz.
The remaining two clusters whose radio powers are ∼11 times below the expected values are
most likely to be in the ‘off-state’ as has been postulated in some of the models of radio halo
formation.
|
|---|