Monday, September 30, 2013
Astronomy Tea Talk
Unveiling the Progenitors of Short-duration Gamma-ray Bursts
Wen-fai Fong, cfa Harvard
While long-duration gamma-ray bursts (GRBs, duration > 2 sec) are linked to the catastrophic death of massive stars, the progenitors of short-duration GRBs (duration < 2 sec) are less certain. From the past decade of observations, the most favored progenitor is the coalescence of two compact objects, either involving two neutron stars or a neutron star and a black hole. Such systems are the premier candidates for gravitational wave signals, which is one of the most anticipated discoveries of the century. Thus, understanding the progenitors and fundamental explosion properties of short GRBs can inform our understanding of the electromagnetic counterparts to gravitational waves. In this talk, I investigate three major open areas in short GRBs: their host populations, their opening angles, and their sub-parsec explosion environments, and demonstrate several lines of observational evidence linking short GRBs to compact object merger progenitors. From their host galaxies, I present the galaxy type demographics, global stellar population properties, locations of short GRBs within their hosts, and their locations with respect to their host light distributions, and find that these properties are well matched to expectations for a compact object merger origin. From their afterglows, I present the latest constraints on the circumburst densities and opening angles, the latter of which directly affects the true energy scale and event rate. Finally, I investigate the next steps for observations of short GRBs in the upcoming era of gravitational wave astronomy.