Constraining short gamma-ray burst jet properties with gravitational waves and gamma rays

Understand

Gamma-ray burst (GRB) prompt emission is highly beamed, and understanding the jet geometry and beaming configuration can provide information on the poorly understood central engine and circum-burst environment.

• Prior to the advent of gravitational-wave astronomy, astronomers relied on observations of jet breaks in the multi-wavelength afterglow to determine the GRB opening angle, since the observer's viewing angle relative to the system cannot be determined from the electromagnetic data alone.
• Gravitational-wave observations, however, provide an independent measurement of the viewing angle.
• We describe a Bayesian method for determining the geometry of short GRBs using coincident electromagnetic and gravitational-wave observations.