Merger of Massive Black Holes using N-Body Simulations with Post-Newtonian Corrections

TL;DR

This study uses high-resolution N-body simulations with Post-Newtonian corrections to explore the evolution of massive black hole binaries during galaxy mergers, highlighting their potential to coalesce within a Hubble time and implications for gravitational wave detection.

Contribution

It introduces detailed N-body simulations incorporating full Post-Newtonian corrections to model black hole binary evolution during galactic mergers, emphasizing eccentricity effects.

Findings

Black hole binaries can merge within less than a Hubble time from 100 pc separations.

High initial eccentricities persist at small separations, affecting gravitational wave signals.

Eccentricities at small separations may influence LISA gravitational wave data analysis.

Abstract

We present preliminary results from self-consistent, high resolution direct {\it N}-body simulations of massive black hole binaries in mergers of galactic nuclei. The dynamics of the black hole binary includes the full Post-Newtonian corrections (up to 2.5PN) to its equations of motion. We show that massive black holes starting at separations of 100 pc can evolve down to gravitational-wave-induced coalescence in less than a Hubble time. The binaries, in our models, often form with very high eccentricity and, as a result, reach separations of 50 Schwarzschild radius with eccentricities which are clearly distinct from zero -- even though gravitational wave emission damps the eccentricity during the inspiral. These deviations from exact circular orbits, at such small separations, may have important consequences for LISA data analysis.