Speaker: Matthew Kerr , US Naval Research Laboratory
Abstract: The Fermi Large Area Telescope (LAT) has now detected gamma-ray pulsations from over 100 millisecond pulsars, and its <300ns times tamping and nearly-unchanged experimental setup enable high-precision pulsar timing over its 15-year baseline. It is thus a "Gamma-ray Pulsar Timing Array" (PTA). Gamma rays are unaffected by propagation through the ionized interstellar medium, and the high-energy data thus enable the separation of propagation effects from the "spin noise" intrinsic to pulsars, perhaps arising from crustal superfluid turbulence. This capability in turns provides a clean measurement the correlated signals expected to be induced by nHz gravitational waves from merging supermassive black holes. I will compare this approach with radio PTAs and present recent results from the Gamma-ray PTA. In a second part, I will also present an overview and early results from Glowbug, a sensitive gamma-ray burst experiment built at NRL and recently launched to the International Space Station. Its large area and sensitive onboard burst detection algorithm will improve the odds of detecting short gamma-ray bursts associated with neutron star mergers, and its primary mission will completely overlap the O4 observing run of LIGO/Virgo/Kagra.