Black hole demographics from TDE modeling

TL;DR

This paper models the rate of tidal disruption events (TDEs) to infer black hole demographics, reconciling theoretical predictions with observed TDE rates through statistical analysis of the black hole mass function.

Contribution

It introduces a theoretical framework combining Fokker-Planck calculations and a Schechter black hole mass function to estimate TDE detection rates and resolve rate discrepancies.

Findings

Theoretical TDE rates are higher than observed but are reconciled through statistical averaging.

A fit of the model to observed TDE rates constrains the Schechter parameters of the black hole mass function.

The study explains the rate tension between observations and theory by considering the black hole mass distribution.

Abstract

The occurrence rate of tidal disruption events (TDEs) by survey missions depend on the black hole mass function of the galaxies, properties of the stellar cusp and mass of the central black hole. Using a power law density profile with Kroupa mass function, we solve the steady state Fokker-Planck to calculate the theoretical capture rate of stars by the black hole. Using a steady accretion model, the Schechter black hole mass function (BHMF) and the cosmological parameters, we calculate the detection rate of TDEs for various surveys which is then fit with the observed TDE rates to extract the Schechter parameters. The rate tension between observation ($\sim 10^{-5}~{\rm yr^{-1}}$) and theory ($\sim 10^{-4}~{\rm yr^{-1}}$) for individual galaxies is explained by the statistical average over the BHMF.