Fermi-Lat Observations of Ligo/Virgo Event Gw170817
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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We present the Fermi Large Area Telescope LAT observations of the binary neutron star merger event GW170817 and the associated short gamma-ray burst SGRB GRB 170817A detected by the Fermi Gamma-ray Burst Monitor. The LAT was entering the South Atlantic Anomaly at the time of the LIGOVirgo trigger tGW and therefore cannot place constraints on the existence of high-energy E 100 MeV emission associated with the moment of binary coalescence. We focus instead on constraining high-energy emission on longer timescales. No candidate electromagnetic counterpart was detected by the LAT on timescales of minutes, hours, or days after the LIGOVirgo detection. The resulting flux upper bound at 95 C. L. from the LAT is 4.5. x. 10-10 erg cm-2 s-1 in the 0.1-1 GeV range covering a period from tGW. . 1153 s to tGW. . 2027 s. At the distance of GRB 170817A, this flux upper bound corresponds to a luminosity upper bound of 9.7. x. 1043 erg s-1, which is five orders of magnitude less luminous than the only other LAT SGRB with known redshift, GRB 090510. We also discuss the prospects for LAT detection of electromagnetic counterparts to future gravitational-wave events from Advanced LIGOVirgo in the context of GW170817GRB 170817A.