On the jet structure of short Gamma-ray bursts through X-ray light curve modeling

En-Tzu Lin^1*, Fergus Hayes², Gavin P. Lamb³, Albert K.H. Kong¹, Ik Siong Heng²

¹Institute of Astronomy, National Tsing Hua University, Hsinchu, Taiwan
²Institute for Gravitational Research, University of Glasgow, Glasgow, UK
³Department of Physics and Astronomy, University of Leicester, Leicester, UK

* Presenter:En-Tzu Lin, email:entzulin@gapp.nthu.edu.tw

Mergers of binary neutron stars (BNS) have been long considered as progenitors of short gamma-ray bursts (GRBs). This idea was confirmed by the detection of the gravitational wave event GW170817 associated with GRB170817A observed by the Fermi gamma-ray telescope at around 2s post-merger. Follow-up monitoring on GRB170817A later shows that a structured jet seen off-axis can explain its afterglow light curve. With the number of BNS events expected to increase in the coming LIGO-VIRGO-KAGRA joint observation era, observing GRB afterglow light curves as well as adopting the constraints from gravitational wave observations should help us resolve the structure of these jets. In this work, we performed quick parameter estimation on simulated GRB X-ray light curves using an interpolated physical GRB model. This leads to a reduced computational time from days to a few minutes. It will allow us to explore different jet models and enable fast model comparison in the future. The goal of this project is to conduct a statistical study to examine how future multi-messenger observations can reveal the intrinsic structure of GRB jets.

Keywords: Binary neutron star, Gamma-ray burst, Afterglow