Fermi Gamma-ray Space Telescope

Searches for Gamma-ray Counterparts to Gravitational-Wave Sources with the Fermi Large Area Telescope

Nicola Omodei
(Nicola Omodei, Giacomo Vianello, Daniel Kocevski, Judith Racusin, on behalf of the Fermi LAT collaboration)


As the first detection of a Gravitation Wave (GW) event arising from the coalescence of two stellar-mass Black Holes (BH) was announced by LIGO, a new era for astronomy began. Searches for electromagnetic (EM) counterpart of GW event is of fundamental importance, as increases the confidence in the GW detection and helps characterize the physical parameters of the merger. Another breakthrough came with the detection of GRB 170817A by the Fermi Gamma-ray Burst Monitor (GBM) 1.7 seconds after the LIGO-Virgo detection of the binary neutron star merger GW170817, which led to important insights into the physics of compact object mergers and their emission components. The Fermi Large Area Telescope (LAT), is sensitive to photons with energies greater than 30 MeV up to several hundred GeV. A large boosting factor is required at the source to produce photons at these energies, likely due to a relativistic jet forming at the time of the merging of the binary system. Even if we eagerly wait for a detection of a signal in the LAT, a non detection will still be of fundamental help in constraining the physics of the object, such as the presence of a jet and its alinement with the line of sight. In this talk I will describe the Large Area Telescope (LAT) capabilities and pipelines for gravitational wave counterpart searches. The observations of gravitational wave counterparts provide unique insights into the physics of neutron stars and gamma-ray bursts, and implications for fundamental physics.