The hangup effect in unequal mass binary black hole mergers and further studies of their gravitational radiation and remnant properties

TL;DR

This paper presents extensive numerical simulations of spinning black hole mergers with unequal masses, analyzing the hangup effect, and provides improved models for remnant properties and gravitational wave signals to aid in gravitational wave data analysis.

Contribution

It introduces new simulations covering a broad parameter space and develops improved fitting formulas for remnant properties and gravitational wave characteristics.

Findings

Identified the spin variable controlling the number of orbits before merger.

Developed improved fitting formulas for remnant mass, spin, and recoil velocity.

Enhanced waveform models for gravitational wave parameter estimation.

Abstract

We present the results of 74 new simulations of nonprecessing spinning black hole binaries with mass ratios $q=m_1/m_2$ in the range $1/7\leq q\leq1$ and individual spins covering the parameter space $-0.95\leq\alpha_{1,2}\leq0.95$ with one runs with spins of $\pm0.95$. We supplement those runs with 107 previous simulations to study the hangup effect in black hole mergers, i.e. the delay or prompt merger of spinning holes with respect to non spinning binaries. We perform the numerical evolution for typically the last ten orbits before the merger and down to the formation of the final remnant black hole. This allows us to study the hangup effect for unequal mass binaries leading us to identify the spin variable that controls the number of orbits before merger as $\vec{S}_{hu}\cdot{\hat{L}},$ where $\vec{S}_{hu}=(1+\frac12\frac{m_2}{m_1})\vec{S}_1+(1+\frac12\frac{m_1}{m_2})\vec{S}_2$. We also combine the total results of those 181 simulations to obtain improved fitting formulae for the remnant final black hole mass, spin and recoil velocity as well as for the peak luminosity and peak frequency of the gravitational strain, and find new correlations among them. This accurate new set of simulations enhances the number of available numerical relativity waveforms available for parameter estimation of gravitational wave observations.