Searching for supermassive black hole binaries in the era of multi-messenger astronomy

Supermassive black hole binaries (SMBHBs) are a natural consequence of galaxy mergers. They should be fairly common in galactic nuclei, but they remain undetected at small separations. These sources are extremely important both for extragalactic astronomy and for fundamental physics, since they are the strongest sources of low-frequency gravitational waves (GWs). They can be identified as quasars with periodic variability in electromagnetic waves or from their strong gravitational radiation. I will discuss the discovery of SMBHB candidates in time-domain surveys, along with ongoing efforts to confirm their binary nature with multi-wavelength observations. I will also describe efforts to detect GWs from merging SMBHBBs with Pulsar Timing Arrays, as well as constraints on tentative binaries in the local universe derived from the most recent NANOGrav dataset. With the first detection on the horizon, I will explore synergies between electromagnetic and GW observations and the tremendous promise for multi-messenger discoveries of SMBHBs, especially in the upcoming era of the Vera Rubin Observatory (formerly known as LSST).

BIO: M. Charisi got her PhD from Columbia University in 2017 and received a fellowship from the North American Nanohertz Observatory for Gravitational waves (NANOGrav) to join the theoretical astrophysics (TAPIR) group at Caltech. Her research is at the intersection of time-domain and gravitational-wave astrophysics. Her expertise is on electromagnetic searches for sub-parsec supermassive black hole binaries and she has led one of the first systematic studies to identify quasars with periodic variability in time-domain surveys. On behalf of NANOGrav, she is leading the astrophysical interpretation of the NANOGrav upper limits on low-frequency GWs.

Exit interview: Thurs 1/30, 3:00pm NPB 2165

Host:  Imre Bartos