TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 868 5298 8404

ABSTRACT: Short gamma-ray bursts (GRBs) are now confidently associated with neutron star mergers. In the past decade, little attention has been paid to the extended emission, which lasts for about 100 seconds and is spectrally soft compared to the short-duration, hard prompt emission in these sources. We study the late-time accretion onto the merger remnant (most likely a spinning black hole) on previously unexplored timescales of minutes to hours and propose a simple model for the extended emission based on our findings. We further predict the existence of "orphan extended emission" (without the short GRB) as a promising EM counterpart for neutron star mergers, observable by current/future wide-field X-ray instruments like Einstein Probe and SVOM. This model also predicts narrow-band spectral features in the kilonova, potentially detectable by JWST.