Non-thermal emission and dynamical state of massive galaxy clusters from
  CLASH sample
  Massive galaxy clusters are the most violent large scale structures
undergoing merger events in the Universe. Based upon their morphological
properties in X-rays, they are classified as un-relaxed and relaxed clusters
and often host (a fraction of them) different types of non-thermal radio
emitting components, viz., haloes, mini-haloes, relics and phoenix within their
Intra Cluster Medium (ICM). The radio haloes show steep (alpha = -1.2) and
ultra steep (alpha < -1.5) spectral properties at low radio frequencies, giving
important insights on the merger (pre or post) state of the cluster. Ultra
steep spectrum radio halo emissions are rare and expected to be the dominating
population to be discovered via LOFAR and SKA in the future. Further, the
distribution of matter (morphological information), alignment of hot X-ray
emitting gas from the ICM with the total mass (dark + baryonic matter) and the
bright cluster galaxy (BCG) is generally used to study the dynamical state of
the cluster. We present here a multi wavelength study on 14 massive clusters
from the CLASH survey and show the correlation between the state of their
merger in X-ray and spectral properties (1.4 GHz - 150 MHz) at radio
wavelengths. Using the optical data we also discuss about the gas-mass
alignment, in order to understand the interplay between dark and baryonic
matter in massive galaxy clusters.
