Lighting Up Electromagnetic Counterparts Across the Gravitational Wave Spectrum

John Ruan

Bishop's

High-frequency gravitational waves from stellar-mass compact object binaries now been detected by LIGO, while low-frequency gravitational waves from individual supermassive black holes binaries at the centres of galaxies will soon be detected by pulsar timing arrays in the near future. Many key science goals of these new frontiers rely on 'multi-messenger' observations, using a combination of both 'cosmic messengers' of gravitational waves and electromagnetic emission. I will discuss two recent advances in understanding the electromagnetic counterparts of gravitational waves, at both high and low frequencies. First, I will discuss how the abundance pattern of heavy r-process elements produced in binary neutron star mergers can be inferred from optical spectroscopy of their resultant kilonova explosions. Our results from applying this approach to the GW170817 binary neutron star merger show that the kilonova ejecta produced an r-process abundance pattern that is remarkably similar to that of our Galaxy, which suggests that these mergers are the origin of the heaviest elements in the Milky Way. Second, I will discuss new insights into the properties of galaxies hosting supermassive black hole binaries, based on cosmological simulations of galaxy formation. I will show how their unique morphologies and stellar kinematics can be used to identify the host galaxy of the first supermassive black hole binary that will be detected in gravitational waves by pulsar timing array experiments.

Date:	Thursday, 26 October 2023
Time:	11:30
Where:	All
	Pavillon MIL A-3561