On to Off: Predictions for the Radio Afterglows of Neutron Star Mergers
Abstract
The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Observatory detect gravitational wave (GW) emission from neutron star mergers. When LIGO/Virgo detect a neutron star merger, fully characterizing the event is challenging due to fairly poor localizations of ~10-100's of square degrees, and relies on the detection of an electromagnetic signal. To potentially improve searches following GW events, we present a study to characterize the behavior of radio off-axis afterglows from neutron star mergers. Assuming that the properties of neutron star mergers are drawn from the same distributions as those of short gamma-ray bursts (GRBs), we used observations of on-axis short GRBs (θobs=0) to predict the behavior of off- axis afterglows (θobs>0) with BOXFIT. We sampled from the distributions of inferred kinetic energies and densities of on-axis short GRB afterglows for our simulation parameters. Overall, the light curves demonstrate that when we incorporate the distributions of energies and densities from short GRBs, there is a large diversity in expected light curve behavior. We find that for θobs=10°, the light curves peak at or above 10-2 mJy that can be detected by our most sensitive facilities; while for θobs=60°, the light curves peak at or above 10-4 mJy, which is beyond the reach of current facilities. Ultimately, our results show the critical role timing plays in our observations, as well as the limited return of deeper observations past a certain depth. This is a proof-of-concept study, and we have developed a multi-use tool that allows for adaptation to other electromagnetic counterpart models. Our results can be reproduced and also tested at other angles through user desired input.
- Publication:
-
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23324805E