Mechanism of GRB Emission

Emission from gamma-ray burst (GRB) jets is complicated by the presence of free neutrons, magnetic fields, and random variability. This project is a systematic study of the jet radiative history, from the early blackbody stage through neutron migration and collisional heating to internal shocks and neutron decay, culminating in the external blast wave. Recent work by the present researcher shows that the main component of GRB emission is naturally produced at the photosphere of the relativistic jet heated by nuclear and Coulomb collisions. The current study will use three state-of-the-art numerical codes that calculate radiative transfer, collisional processes, and collective plasma processes in the expanding jet. The ultimate goal is to reconstruct the radiative history of GRB jets and estimate their Lorentz factors and magnetization.

GRB research impacts various fields in astronomy, from the theory of stellar core-collapse to jets in active galactic nuclei to early star formation in the Universe to future gravitational wave astronomy to new theories of mass extinction on the Earth. GRB research also impacts fundamental physics through understanding new properties of matter under extreme conditions. The research will involve graduate and undergraduate students, and the results will be disseminated at conferences and taught as part of high-energy astrophysics courses at Columbia University.