Theory of off-axis and gravitational wave events

Abstract

GW170817 was not merely an absolute breakthrough in gravitational wave astrophysics and a first in multi-messenger astronomy. The quality and diversity of the electro-magnetic counterpart emission is staggering on its own as well, including unprecedented kilonova spectra and a broadband off-axis gamma-ray burst afterglow that has progressed along a trajectory of rise and decay and by now has even been measured using very large baseline interferometry. For these proceedings, I will summarize the points for discussion that I presented during the workshop regarding off-axis short gamma-ray bursts and their (un-)successful jets and their emission. Given that developments are currently moving very fast in the field, I also touch on some results that have appeared in the literature following the Vulcano meeting.