Abstract Details
| Name: Sameer Salunkhe Affiliation: S P Pune University, Pune Conference ID: ASI2019_344 Title : Low-frequency radio study of MACS clusters using the GMRT at 610 and 235 MHz Authors and Co-Authors : Sameer Salunkhe, Surajit Paul, Abhirup Datta and Huib T. Intema Abstract Type : Oral Abstract Category : Extragalactic Astronomy Abstract : Studies have shown that galaxy cluster mergers produce shocks and turbulence in the intra-cluster medium, the possible event responsible for creating observed radio relics as well as the halo structures. Observed radio halos and relics thus can help us to trace back the cluster formation history. In order to understand the formation dynamics, as a pilot project, we have observed four candidates from the MACS (MAssive Cluster Survey) catalogue in radio. Clusters are chosen from their disturbed morphology in X-ray and weak lensing study to ensure their merging state. Observations were carried out simultaneously at 610 and 235 MHz with the GMRT. Among the proposed four clusters, three of them have been detected with expected diffuse radio emissions. We report an unusually flat spectrum giant radio halo at a low frequency of a previously known halo-relic cluster MACSJ0014.3-3022. Our observations have also revealed an ongoing second merger along with a close-by high-speed (about 1800 km/s ) merger-shock. This shock has been estimated to have formed recently (not beyond 400 Myr), thus providing a clue to the flat spectrum of the halo. We also report the detection of diffuse and very faint (with sizes about 0.4-0.5 Mpc) radio relics in MACSJ0025.4-1222 and MACSJ0152.5-2852 clusters. In both the clusters, the relics are found well inside the virial radius instead of their usual peripheral location and we also find the upper limit for radio halo for these two clusters. These high-redshift objects (z=0.584 and 0.413) are thus the example of one of the few earliest and youngest known merging galaxy clusters. We also report the non-detection of any diffuse radio emission from the MACSJ1931-2635 cluster at the reported rms levels in our study. |