Title:
Black hole inspirals embedded in accretion disks (Can LISA probe
migration?)

Abstract:
The coalescence of a compact object into a supermassive black hole emits
gravitational waves (GWs) which in a particular frequency range will be
detectable by the space-based interferometer LISA. A fraction of these
events may occur in the accretion disks of active galactic nuclei, where
torques exerted by the gas can alter the inspiral and subsequent GW
phase evolution. I will present a suite of two-dimensional simulations
with the hydrodynamical moving-mesh code DISCO of an isothermal, viscous
disk with an embedded inspiralling BH, focusing on the case of
intermediate mass ratio inspirals. The measured torques exerted by the
gas (analogous to planetary migration torques) are different from
previous analytical estimates in their strength, direction, and temporal
evolution, all of which are sensitive to the BH mass and the disk
parameters. Over thousands of orbits, interaction with the gas disk
imparts a phase drift (a 'gas imprint') in the GW waveform, which - if
detectable by LISA - can carry information on AGN disk properties. I
will discuss how gas torques evolve throughout an inspiral and how they
vary with simulation parameters, followed by estimates of detectability
and some critical next steps.