Abstract Details

Name: ANKUR GHOSH
Affiliation: SRF, ARIES
Conference ID: ASI2020_151
Title : Search for magnetar emission from very late time radio observations of short Gamma- Ray Bursts.
Authors and Co-Authors : Author- Ankur Ghosh Co-authors- Dr. Kuntal Misra S.V. Cherukuri Dr. L. Resmi Dr. K. G. Arun Dr. Amitesh Omar
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : Abstract: Coalescence of inspiral binary neutron stars (BNS) system, giving rise to short Gamma-Ray Bursts (GRBs), are one of the most probable candidates for Gravitational Waves (GWs). The resultant product of these merger events may in some cases gives birth to a rapidly rotating, highly magnetized and hyper-massive neutron star which is short-lived and can potentially survive for a few milliseconds before collapsing to a black hole. Such a remnant has been proposed as an explanation for the exotic change (X-ray plateau, late time X-ray excess) in the X-ray light-curves. This hyper-massive NS or magnetar has a huge amount of rotational energy (≥ 10^52 erg), the majority of which is imparted to the surrounding ejecta via the spin-down process. The interaction between the sub-relativistic or non-relativistic ejecta and circum-stellar medium (CSM) is responsible for the late-time radio emission seen at the deceleration timescale. In this work, our aim is to search for late time radio emission, in short GRBs with potential magnetar signatures, using Giant Meter-wave RadioTelescope (GMRT) at rest-frame time scales of nearly 5 - 10 years after the burst. Observations of four short GRBs in 1400, 625 and 325 MHz results in a non-detection placing stringent upper limits. These upper limits are used to constrain the ambient medium density, magnetar rotational energy and ejecta velocity using the magnetar and non-magnetar models for different ejecta masses.