A Joint Fermi-Gbm and Ligo/Virgo Analysis of Compact Binary Mergers from the First and Second Gravitational-Wave Observing Runs
We present results from offline searches of Fermi Gamma-ray Burst Monitor (GBM) data for gamma-ray transients coincident with the compact binary coalescences observed by the gravitational-wave (GW) detectors Advanced LIGO and Advanced Virgo during their first and second observing runs. In particular, we perform follow-up for both confirmed events and low significance candidates reported in the LIGO/Virgo catalog GWTC-1. We search for temporal coincidences between these GW signals and GBM-triggered gamma-ray bursts (GRBs). We also use the GBM Untargeted and Targeted subthreshold searches to find coincident gamma-rays below the onboard triggering threshold. This work implements a refined statistical approach by incorporating GW astrophysical source probabilities and GBM visibilities of LIGO/Virgo sky localizations to search for cumulative signatures of coincident subthreshold gamma-rays. All search methods recover the short gamma-ray burst GRB 170817A occurring ∼1.7 s after the binary neutron-star merger GW170817. We also present results from a new search seeking GBM counterparts to LIGO single-interferometer triggers. This search finds a candidate joint event, but given the nature of the GBM signal and localization, as well as the high joint false alarm rate of 1.1 10-6 Hz, we do not consider it an astrophysical association. We find no additional coincidences.
R. Hamburg et al., "A Joint Fermi-Gbm and Ligo/Virgo Analysis of Compact Binary Mergers from the First and Second Gravitational-Wave Observing Runs," Astrophysical Journal, vol. 893, no. 2, Institute of Physics - IOP Publishing, Apr 2020.
The definitive version is available at https://doi.org/10.3847/1538-4357/ab7d3e
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20 Apr 2020