Abstract Details

Name: RAHUL GUPTA
Affiliation: ARIES Nainital
Conference ID: ASI2020_165
Title : Progenitor and environment of complete sample of Ultra-long Gamma Rays Bursts
Authors and Co-Authors : Rahul Gupta, S. B. Pandey, Vikas Chand and Varun Bhalerao
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : Ultra-long Gamma Rays Bursts (UlGRBs) are an interesting class of Gamma ray burst (GRBs) lasting several hours in gamma-rays than typical long GRBs (LGRBs). Progenitor and environment of UlGRBs are still mysterious and elusive. Many models have been proposed in literature to explain their nature. We present in this work a comparison of prompt emission as well as X-ray afterglow properties of complete sample of Swift detected UlGRBs and LGRBs having T90 duration greater than 100 seconds. For this study, we focus on Swift data to make an homogeneous sample. Observation available up to June 2019 were used to make our gold, silver and bronze samples, based on burst T90 durations. Our findings regarding progenitor of UlGRBs point towards a common central engine for UlGRBs and LGRBs, consistent with collapsar model.  Many other prompt emission properties such as peak energy, hardness ratio and gamma-ray isotropic equivalent energies has been estimated and compared with LGRBs. Broadband fitting of GRBs afterglows data tells us burst explosion parameters and the environment related parameters. For environment of these high energy events, X-ray absorbing column density (NH) are used as a parameter to estimate amount of absorbing material along the line of sight. We have used two different models for quantifying amount of NH along the sight. Earlier study of X-ray absorbing column density evolution of LGRBs confirmed that these events take place in dense, star-forming environments. Our results of NH evolution of UlGRBs shows that these events also take place in dense, star-forming environments, joining as an indirect proof of supernovae association to these bursts. This is the first time when such environmental study of complete sample of UlGRBs has been performed.