Gravitational Waves from Disks Around Spinning Black Holes: Simulations in Full General Relativity

TL;DR

This paper uses full general relativity simulations to study gravitational wave emission from self-gravitating disks around spinning black holes, analyzing instability growth, wave detectability, and electromagnetic signals.

Contribution

It presents the first fully general-relativistic simulations of self-gravitating disks around spinning black holes and assesses their gravitational wave detectability across different mass ranges.

Findings

Instability growth similar to non-spinning cases with spin-induced frequency shifts.

Detectability of gravitational waves from stellar-mass to supermassive black hole systems.

Potential electromagnetic counterparts from these accreting systems.

Abstract

We present fully general-relativistic numerical evolutions of self-gravitating tori around spinning black holes with dimensionless spin $a/M = 0.7$ parallel or anti-parallel to the disk angular momentum. The initial disks are unstable to the hydrodynamic Papaloizou-Pringle Instability which causes them to grow persistent orbiting matter clumps. The effect of black hole spin on the growth and saturation of the instability is assessed. We find that the instability behaves similarly to prior simulations with non-spinning black holes, with a shift in frequency due to spin-induced changes in disk orbital period. Copious gravitational waves are generated by these systems, and we analyze their detectability by current and future gravitational wave observatories for large range of masses. We find that systems of $10 M_\odot$ - relevant for black hole-neutron star mergers - are detectable by Cosmic Explorer out to $\sim300$ Mpc, while DECIGO (LISA) will be able to detect systems of $1000 M_\odot$ ($10^5M_\odot$) - relevant for disks forming in collapsing supermassive stars - out to cosmological redshift of $z\sim5$ ($z\sim 1$). Computing the accretion rate of these systems we find that these systems may also be promising sources of coincident electromagnetic signals.