Discovery of large-scale diffuse radio emission and of a new galaxy
  cluster in the surroundings of MACSJ0520.7-1328
  We report the discovery of large-scale diffuse radio emission South-East of
the galaxy cluster MACS J0520.7-1328, detected through high sensitivity Giant
Metrewave Radio Telescope 323 MHz observations. This emission is dominated by
an elongated diffuse radio source and surrounded by other features of lower
surface brightness. Patches of these faint sources are marginally detected in a
1.4 GHz image obtained through a re-analysis of archival NVSS data.
Interestingly, the elongated radio source coincides with a previously
unclassified extended X-ray source. We perform a multi-wavelength analysis
based on archival infrared, optical and X-ray Chandra data. We find that this
source is a low-temperature (~3.6 keV) cluster of galaxies, with indications of
a disturbed dynamical state, located at a redshift that is consistent with the
one of the main galaxy cluster MACS J0520.7-132 (z=0.336). We suggest that the
diffuse radio emission is associated with the non-thermal components in the
intracluster and intergalactic medium in and around the newly detected cluster.
We are planning deeper multi-wavelength and multi-frequency radio observations
to accurately investigate the dynamical scenario of the two clusters and to
address more precisely the nature of the complex radio emission.
