APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Gabriela Sato-Polito (IAS, Princeton )
Title: Gravitational-wave signatures of supermassive black holes
Date (JST): Thu, Feb 15, 2024, 13:30 - 15:00
Place: Seminar Room A
Abstract: Pulsar timing arrays (PTAs) consist of a set of regularly monitored millisecond pulsars with extremely stable rotational periods. The arrival time of pulses can be altered by the passage of gravitational waves (GWs) between them and the Earth, thus serving as a galaxy-wide GW detector. Evidence for the first detection of low-frequency (~nHz) gravitational waves has recently been reported across multiple PTA collaborations, opening a new observational window into the Universe. Although the origin of the GW signal is yet to be determined, the dominant sources are expected to be inpiralling supermassive black holes (SMBHs). I will discuss how the recent GW detection can complement existing electromagnetic observations, enriching our picture of the most massive black holes in the Universe. Following the recent detection of a homogeneous component of the GW background, spatial fluctuations are a compelling next observational target. I will discuss the spatial fluctuations produced by SMBHs and what they can teach us about this population.