Pulsar Timing Arrays: a window into dark matter and gravity

Pulsar Timing Array (PTA) facilities are powerful experiments timing an ensemble of galactic millisecond pulsars and have recently reported strong evidence of a stochastic gravitational wave background, most likely originating from inspiraling supermassive black hole binaries.

While a primary objective is to characterize this signal and the underlying population of astrophysical sources, PTAs also offer a unique window into fundamental physics. In this talk, I will demonstrate how PTAs can probe two distinct aspects of fundamental physics: on the one hand, the nature of dark matter, including its interactions with the Standard Model and its gravitational coupling; on the other hand, modified theories of gravity that influence the inspiral of supermassive black hole binaries.