CRA Seminar: Zoltan Haiman (Columbia, on sabbatical at GT)

TITLE: Gravitational wave and electromagnetic signatures of binary
black holes with circumbinary gas

ABSTRACT: Binary black holes (BHBs) embedded in dense gas hold the
promise of so-called “multi-messenger astrophysics”: when they are
detected both through gravitational waves (GWs) and electromagnetic
(EM) observations, they will enable novel science.  This is true both
for massive BHBs, whose GWs will be detectable by the future LISA
satellite and by on-going pulsar timing arrays (PTAs), as well as for
stellar-mass BHBs detected through ground-based GW detectors.  In both
cases, identifying the coalescing binaries through their EM signatures
will help clarify their astrophysical origin and yield novel probes of
cosmology, fundamental physics, and accretion physics.  In this talk,
I will describe how circumbinary gas may produce characteristic EM
signatures for both massive and stellar-mass BHBs, based on analytic
models as well as hydrodynamical simulations.  I will also argue that
in both cases, some coalescing binaries may have already been detected
in optical surveys, providing clues about their origin.