Dynamics of marginally trapped surfaces in a binary black hole merger: Growth and approach to equilibrium

TL;DR

This paper numerically investigates the evolution of marginally trapped surfaces during a binary black hole merger, analyzing horizon properties, growth, and approach to equilibrium to enhance understanding of black hole coalescence.

Contribution

It provides a detailed numerical analysis of horizon dynamics, fluxes, and multipole moments during black hole mergers, including the onset of ringdown and horizon-wave correlations.

Findings

Final black hole approaches Kerr equilibrium

Identified the start of the linear ringdown phase

Found correlations between horizon fluxes and gravitational waves

Abstract

The behavior of quasi-local black hole horizons in a binary black hole merger is studied numerically. We compute the horizon multipole moments, fluxes and other quantities on black hole horizons throughout the merger. These lead to a better qualitative and quantitative understanding of the coalescence of two black holes; how the final black hole is formed, initially grows and then settles down to a Kerr black hole. We calculate the rate at which the final black hole approaches equilibrium in a fully non-perturbative situation and identify a time at which the linear ringdown phase begins. Finally, we provide additional support for the conjecture that fields at the horizon are correlated with fields in the wave-zone by comparing the in-falling gravitational wave flux at the horizon to the outgoing flux as estimated from the gravitational waveform.