Name: Nayana A.J.
Affiliation: Indian Institute of Astrophysics
Conference ID : ASI2022_199
Title : Low-frequency radio view of a fast-blue optical transient - AT2018cow
Authors : Nayana A.J. and Poonam Chandra
Abstract Type: Oral
Abstract Category : Extragalactic Astronomy
Abstract : Fast-Blue Optical Transients (FBOTs) is a new class of short-time scale events that exhibit a wide range of observational characteristics (luminosities, energetics, and environments), indicating the diversity in their origin. Radio emission from these events is understood to be due to the interaction of the fast-moving ejecta from the explosion and the circumstellar medium (CSM). Detailed radio follow-up observations and modeling give information about the environmental density, shock velocities, and mass-loss rate of the progenitor system. Low-frequency radio observations are particularly interesting since these observations probe the extended environment complimenting the information from early high-frequency observations. We present the low-frequency radio observations and modeling of an FBOT, AT2018cow with the upgraded Giant Metrewave Radio Telescope (uGMRT). Our data are best modeled as an inhomogeneous synchrotron emitting region expanding into the ionized CSM. We estimate the mass-loss rate of the progenitor star and shock parameters at multiple epochs post-explosion. Our study suggests that the progenitor has gone through an enhanced phase of mass-loss close to its end-of-life creating a dense CSM shell near AT2018cow.