A study of diffuse radio sources and X-ray emission in six massive
  clusters
  The goal of the present 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 {\it 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 $L_{x}$--$P_{1.4GHz}$ plot.
{However, we found ultra-steep spectrum radio halo in the MACSJ0417.5-1154
cluster whose rest-frame cut-off frequency is at $\sim$ 900 MHz}. The remaining
two clusters whose radio powers are $\sim$ 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.
