Signatures from late-time disk accretion in neutron star mergers - Wenbin Lu - 03/08/2024

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Published 2024-03-08

This is a high-level research talk designed for professional astronomers. It is part of the Caltech Astronomy TAPIR seminar series, roughly hour-long presentations given by top scientists from around the world to the members of our department. All are welcome to watch these presentations; however, for talks specifically designed for the general public, please see our Caltech Astro Outreach channel: youtube.com/c/caltechastro

Date: 03/08/2024
Speaker: Wenbin Lu - UC Berkeley
Title: Signatures from late-time disk accretion in neutron star mergers
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.

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