Suppression of stellar tidal disruption rates by anisotropic initial conditions

TL;DR

This paper investigates how certain initial stellar distributions, influenced by binary black holes or anisotropic velocities, suppress the rate of stellar tidal disruptions near supermassive black holes, especially in younger galactic nuclei.

Contribution

It introduces time-dependent models with specific initial conditions to quantify the suppression of stellar disruption rates due to anisotropic distributions.

Findings

Suppression of disruption rates in young galactic nuclei with less than 0.1 relaxation times.

Reduced observable tidal disruption flares in galaxies with black hole masses over 10^7 solar masses.

Initial conditions with phase space gaps or tangential anisotropy significantly decrease star capture flux.

Abstract

We compute the rates of capture of stars by supermassive black holes, using time-dependent Fokker--Planck equation with initial conditions that have a deficit of stars on low-angular-momentum orbits. One class of initial conditions has a gap in phase space created by a binary black hole, and the other has a globally tangentially-anisotropic velocity distribution. We find that for galactic nuclei that are younger than ~0.1 relaxation times, the flux of stars into the black hole is suppressed with respect to the steady-state value. This effect may substantially reduce the number of observable tidal disruption flares in galaxies with black hole masses M>10^7 Msun.