Abstract Details

Name: Surajit Paul
Affiliation: SP Pune University
Conference ID: ASI2020_451
Title : Future perspective on radio astronomy with low mass clusters: Discovery of diffuse radio emission in low mass cluster Abell 1697
Authors and Co-Authors : Surajit Paul, Sameer Salunkhe, Prateek Gupta, Satish Sonkamble, Tony Mroczkowski, and Somak Raychaudhury
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : We report the discovery of a putative radio relic, 830 kpc in length and found toward the outskirts of galaxy cluster Abell 1697 ($z=0.181$), using the LOFAR Two Meter Sky Survey (LoTSS) at 144 MHz. With an X-ray-inferred mass of $M_{500}^{X-ray}=2.9^{+0.8}_{-0.7}\times10^{14}~\rm{M_{\odot}}$, this places Abell 1697 among the least massive relic hosts. The relic is also detected at 325 MHz WENSS and at 1.4 GHz in NVSS with an average spectral index of $\alpha(144,325,1400~\rm{MHz})=-0.98\pm0.01$. The relic is trailed by an extended ($790\times550$ kpc) diffuse radio emission towards the cluster center, that is likely an ultra-steep spectrum ($\alpha_{144 \rm{MHz}}^{1.4\rm{GHz}}<-1.84$) radio source. Relics are so far detected more commonly in massive merging systems. Low mass clusters and groups are, however, more affected by mergers and various non-gravitational processes and contain high levels of cosmic-rays, likely due to frequent AGN feedback events. Theoretically, low mass clusters are also expected to have stronger shocks in deeper cores due to its cooler ICM. This would mean, if relics are shock generated, their fraction may be observed to increase significantly in low mass systems as the sensitivity of radio and X-ray surveys improve. The current cluster is a good example of that and future telescopes such as SKA would, therefore, be a game-changer in radio astronomy of low mass clusters.