PIRSA:24100106

Where are the supermassive black holes measured by PTAs?

Sato-Polito, G. (2024). Where are the supermassive black holes measured by PTAs?. Perimeter Institute. https://pirsa.org/24100106

Sato-Polito, Gabriela. Where are the supermassive black holes measured by PTAs?. Perimeter Institute, Oct. 08, 2024, https://pirsa.org/24100106 

          @misc{ pirsa_PIRSA:24100106,
            doi = {10.48660/24100106},
            url = {https://pirsa.org/24100106},
            author = {Sato-Polito, Gabriela},
            keywords = {Cosmology},
            language = {en},
            title = {Where are the supermassive black holes measured by PTAs?},
            publisher = {Perimeter Institute},
            year = {2024},
            month = {oct},
            note = {PIRSA:24100106 see, \url{https://pirsa.org}}
          }

Gabriela Sato-Polito

Institute for Advanced Study (IAS) - School of Natural Sciences (SNS)

Talk number
PIRSA:24100106
Collection
Talk Type
Subject
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 a recent work in which we compare the GW detections by PTAs with the expected signal implied by existing electromagnetic observations in a simple but robust manner. This study suggests that the currently measured GW amplitude is larger than expected by a significant amount. I will then show that additional information regarding the typical number of sources contributing to the background can already be inferred from current PTA data.