Quasars Can Signpost Supermassive Black Hole Binaries

Supermassive black holes (SMBHs) are found in the centers of massive galaxies, and galaxy mergers should eventually lead to SMBH mergers. Quasar activity has long been associated with galaxy mergers, so here we investigate if supermassive black hole binaries (SMBHBs) are preferentially found in quasars, and the inferred probability for quasars to include SMBHBs. Our multimessenger investigation folds together a gravitational wave background signal from NANOGrav, a sample of periodic AGN candidates from the Catalina Real-Time Transient Survey, and a quasar mass function, to get a handle on the fraction of SMBHBs which could be found in quasars. We find at 95% confidence that quasars are up to seven times as likely to host an SMBHB as a random galaxy. Quasars should therefore be prioritized as targets for SMBHB searches in pulsar timing arrays.

Dec 16, 2023 2:10 PM — 2:30 PM