Speaker
Description
The gravitational waves from the binary neutron star merger GW170817 were accompanied by a multi-wavelength electromagnetic counterpart, which confirms the association of the merger with a short gamma-ray burst (sGRB). The afterglow observations implied that the event was accompanied by a narrow, ~5°, and powerful, ~1050 erg, jet. We study the propagation of a Poynting flux-dominated jet within the merger ejecta (kinematic, neutrino-driven, and magneto-rotational instability turbulence-driven) of a neutrino-radiation-GRMHD simulation of two coalescing neutron stars. We find that the presence of a post-merger low-density/low-pressure polar cavity, which arose due to angular momentum conservation, is crucial to let the jet break out. At the same time the ejecta collimates the jet to a narrow opening angle. The collimated jet has a narrow opening angle of ~4°-7° and an energy of 1049-1050 erg, in line with the observations of GW170817 and other sGRBs.
