Inclination estimates from off-axis GRB afterglow modelling

Understand

For gravitational wave (GW) detected neutron star mergers, one of the leading candidates for electromagnetic (EM) counterparts is the afterglow from an ultra-relativistic jet.

• Where this afterglow is observed, it will likely be viewed off-axis, such as the afterglow following GW170817/GRB 170817A.
• The temporal behaviour of an off-axis observed GRB afterglow can be used to reveal the lateral jet structure, and statistical model fits can put constraints on the various model free-parameters.
• Amongst these parameters is the inclination of the system to the line of sight.