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Physics & Astronomy Colloquium – Spring 2020 – Charisi
February 12, 2020 @ 3:30 pm - 5:00 pm
Speaker: Maria Charisi (Caltech)
Title: 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, since they are a missing piece of hierarchical structure formation. They are the strongest sources of low-frequency gravitational waves (GWs) and thus important for fundamental physics. They can be identified as quasars with periodic variability in electromagnetic waves or by Pulsar Timing Arrays due to the strong emission of 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 SMBHBs 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).
Dr. Maria Charisi is a post-doctoral scholar in theoretical astrophysics in the TAPIR group at Caltech. She holds a post-doctoral fellowship from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). She is broadly interested in time-domain and gravitational-wave astronomy. She received a PhD in Astronomy from Columbia University in 2017.