Fermi Gamma-ray Space Telescope

Searching For GRB Counterparts To Gravitational Waves With Fermi GBM

Rachel Hamburg
(Michael Briggs, Adam Goldstein)


The detection of GRB 170817A, the first short gamma-ray burst (SGRB) associated with gravitational waves (GWs) from a binary neutron star merger, has established the Fermi Gamma-ray Burst Monitor (GBM) as a key player in the era of multimessenger astronomy. GBM also triggers on more SGRBs than any other active instrument, making it a likely candidate for detecting future counterparts to GWs. Moreover, GRB 170817A showed the existence of a population of nearby, subluminous SGRBs, which has led to an upward reassessment of the joint GW/GRB detection rate. We present the capability to detect more of these faint bursts through subthreshold searches of GBM data. The Untargeted Search agnostically identifies simultaneous count rate increases in two GBM detectors, while the Targeted Search is initiated by a GW trigger and looks for coherent signal across all detectors. We review improvements to these pipelines and outline how potential counterparts will be disseminated to the follow-up community during LIGO/Virgo’s third observing run. Finally, we highlight how identifying SGRBs associated with GW events can maximize the science return of multimessenger campaigns.