| Abstract : | Radio halos and relics are diffuse, Mpc-sized sources and are associated with the intra-cluster medium (ICM) of galaxy clusters. Their synchrotron spectra indicate the presence of ultra-relativistic charged particles and cluster-wide magnetic fields (~μG levels). The origin of these relativistic charged particles and magnetic fields is unknown. These sources are commonly found in the merging clusters, so it is believed that merger-induced turbulence can accelerate the charged particles. A huge radio halo (~2.9 Mpc) and a radio relic were discovered in Abell 2163 through VLA (1.4 GHz and 321.5/327.5 MHz) and GMRT (153 MHz and 332 MHz) observations. Also, a central flat spectrum ridge was found at the location of the cluster merger through GMRT observations, indicating that the merger can cause acceleration of the charged particles. However, the full extent of radio halo was not detected in GMRT observations. We present uGMRT observations of this cluster in the bands 3 (300-500 MHz) and 4 (550-750 MHz). We have detected radio halo extents of 10 and 12 arcminutes at bands 4 and 3, respectively and also found a region of the flat spectrum at the merger location in the radio halo. At the location of the radio relic, an X-ray shock front was detected. We provide the integrated spectral index of the radio relic, which is consistent with the typical spectral indices of the radio relics that are found at the shock locations. We discuss the results in the context of the complex merger that the cluster is undergoing and the proposed theoretical models for the origin of radio halos and relics. |
