Monday, September 14, 2020 at 12:40

https://cuboulder.zoom.us/j/96981439846

Joe Simon, CU-CASA

"Merging Galaxies & Supermassive Black Hole Binaries: Multi-Messenger Astrophysics with Pulsar Timing Arrays"

Abstract:

Pulsar timing arrays (PTAs) are galactic-scale low-frequency (nHz - μHz) gravitational wave (GW) observatories, which aim to directly detect GWs from supermassive black hole (SMBH) binaries (≥ 107 M⊙). SMBH binaries are predicted products of galaxy mergers and are a crucial step in galaxy formation theories. The primary source of gravitational radiation in the nHz regime is expected to be a stochastic background, formed from the cosmic population of SMBH binaries. In this talk, I will discuss the current state-of- the-art detection approaches to searching for a gravitational wave background in pulsar timing data, including a novel approach to account for errors in Solar System ephemerides, and present the results obtained by analyzing the 12.5-year data release from the North American Observatory for Gravitational Waves (NANOGrav).

Understanding the link between SMBH binaries and the gravitational radiation detected by PTAs is crucial to our community's capability of making meaningful scientific statements using PTA observations. I will end my talk with a discussion of ongoing work which provides a direct translation between PTA data and observable parameters of SMBH binary evolution in galactic cores, including the relation between the mass of the central supermassive black hole and the galactic bulge (the MBH − Mbulge relation) and the coupling between the binary and its galactic environment.

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