Gamma-ray burst afterglow jet analysis In the multi-messenger Era
Nordita Astrophysics seminars
Friday 06 September 2019
Hendrik van Eerten (University of Bath)
Gamma-ray bursts (GRBs) associated with gravitational wave events are, and will likely continue to be, viewed at a larger inclination than their fellow GRBs without gravitational wave detections. As demonstrated by the afterglow of GW170817A, this requires an extension of the common GRB afterglow models which typically assume emission from an on-axis top hat jet. I present an updated characterization of the afterglows arising from neutron star merger jets, utilizing both trans-relativistic numerical calculations and simple analytic approximations of structured outflows. These will serve as a toolkit for both detailed and rapid qualitative modeling and interpretation of afterglows in the multi-messenger era. For example, in many cases, the afterglow temporal slope can be immediately connected to a ratio between the inclination angle and effective half opening angle of the jet. Our models, both numerical and analytic, will be made publicly available as an open source Python package and are readily implemented in statistical analysis packages and population studies (Ryan & van Eerten, manuscript in prep; github.com/geoffryan/afterglowpy). This work extends the jet model that has been used to model GW170817A in a series of papers including our Chandra X-ray afterglow discovery paper (Troja+ 2017).