Searching for supermassive black hole binaries

Supermassive black hole binaries (SMBHBs) are a natural byproduct of galaxy mergers. Yet, they remain undetectable at small separations. A promising method is to identify quasars with periodic variability. I will discuss candidates identified in time-domain surveys, as well as ongoing efforts to confirm their binary nature. I will also describe efforts to detect gravitational waves from SMBHBs with Pulsar Timing Arrays and constraints on tentative binaries in the local universe from the most recent NANOGrav upper limits.

Speaker: Maria Charisi, Caltech