Misc,
Dynamical evolution of massive black hole pairs in the presence of spin-dependent radiative feedback
(2022)cite arxiv:2212.08669.
Abstract
The putative ubiquity of massive black holes (MBH) at the center of galaxies,
and the hierarchical progress of structure formation along the cosmic history,
together necessarily imply the existence of a large population of cosmic MBH
binaries. Such systems are understood to be the loudest sources of
gravitational waves at mHz frequencies, the regime that will be probed by the
next Laser Interferometer Space Antenna (LISA). It has been proposed that the
rate at which MBHs pair and then bind to form binaries is critically dependent
upon the feedback exerted by the MBHs on the surrounding gaseous environment.
Using the publicly available code GIZMO, we perform a suite of simulations
aimed at studying the dynamics of a MBH pair embedded in a gaseous disk on 100
pc scale. By means of dedicated modules, we follow the dynamics of MBHs in the
presence of different spin-dependent radiative feedback models, and compare the
results to a benchmark case with no feedback at all. Our main finding is that
feedback causes the secondary MBH to shrink its orbit at a reduced pace, when
compared to models where feedback is absent. Moreover, such slower inspiral
occurs on eccentric orbits, as feedback has the net effect of hampering the
circularization process. Though idealized in many aspects, our study highlights
and quantifies the importance of including spin-dependent feedback recipes in
hydrodynamic simulations of MBH pairs, and ultimately in assessing the
cosmological coalescence rate of such systems in view of their detection
through gravitational waves.
