Giulia Macario (Observatoire de la Cote d'Azure, Nice)

Giulia Macario Colloquium -- Searching for diffuse large-scale radio emission in cluster of galaxies

Abstract

A growing number of galaxy clusters is nowadays known to host diffuse, large-scale radio sources (up to Mpc and beyond), commonly grouped into radio halos, radio relics and mini-halos on the basis of their location and properties. Their steep-spectrum synchrotron emission probes the presence of non-thermal intracluster components (weak magnetic fields and relativistic particles), that can affect the thermodynamical evolution of the host clusters.
Their origin is still puzzling, thus it is crucial to extend our knowledge of their statistical properties to redshifts higher than those investigated so far, through high sensitivity radio surveys of galaxy clusters.
I will present some preliminary results of the MACS-Planck Radio Halo cluster Project, a large observing program to study a sample of clusters selected from the MACS and the XMM-Planck SZ catalogs in the still unexplored redshift range 0.3-0.45. For this, we recently completed a deep pointed survey of 32 clusters, carried out mainly at low frequency (25 targets with the GMRT at 325 MHz, 7 with ATCA at 2.1 GHz).
I will also present the discovery of very large and complex diffuse emission, serendipitously associated to a new galaxy cluster, previously unclassified and likely related to one the targets of our survey.