Seminar by Chris Tiede on the topic of Supermassive black hole binaries and their environments

Seminar by Chris Tiede, from the Niels Bohr Institute, on the topic of supermassive black hole binaries and their environments.

Title: Why massive black hole binaries may not appear as we expected

Abstract: Recent pulsar timing array observations have found evidence for a stochastic gravitational wave background, likely produced by a cosmic population of inspiraling massive black hole binaries. This same population is also expected to give rise to the black hole mergers that will be measured in the coming decade by the LISA satellites. The next challenge is to identify individual systems and connect their gravitational wave signals to their electromagnetic counterparts. Doing so requires understanding how massive black hole binaries interact with their environments and how those interactions shape the electromagnetic signatures we use to search for them. I will overview the standard picture of binary accretion and how compact massive black hole binaries are typically expected to appear in electromagnetic observations. I will then discuss recent simulation and analytic work suggesting that actively accreting massive black hole binaries may appear more distinct than previously expected, and I will outline potential diagnostics for identifying promising binary candidates in current and upcoming electromagnetic surveys.