Signatures of Circumbinary Disk Dynamics in Astrophysical Binary Populations

This seminar explores how circumbinary disk dynamics influence astrophysical binary populations, presented by Magdalena Siwek from Columbia University. Discover compelling evidence from Pulsar Timing Arrays (PTAs) for a Gravitational Wave Background (GWB) produced by Massive Black Hole Binaries (MBHBs). Learn how circumbinary accretion disks (CBDs) in gas-rich galactic nuclei interact with MBHBs, increasing the amplitude of the GWB while having minimal effect on orbital expansion. Examine how CBD-induced mass ratio evolution and the 'eccentricity attractor' create distinctive signatures in MBHB populations—signatures already detected in stellar binaries. Explore how accretion from CBDs may enable multi-messenger detection through electromagnetic follow-up, with preliminary models showing diverse electromagnetic signatures emitted by MBHBs in CBDs.