Precision tracking of massive black hole spin evolution with LISA

TL;DR

LISA will precisely measure the spin evolution, mass, and other parameters of massive black hole binaries, providing key insights into their origins, dynamics, and galactic environments.

Contribution

This study demonstrates that LISA can accurately track black hole spin evolution and other binary parameters using advanced waveform models and Bayesian inference.

Findings

Black hole spins can be tracked to percent accuracy.

Component masses measurable at sub-percent level.

Sky localization within 0.01 deg².

Abstract

The Laser Interferometer Space Antenna (LISA) will play a vital role in constraining the origin and evolution of massive black holes throughout the Universe. In this study we use a waveform model (IMRPhenomXPHM) that includes both precession and higher multipoles, and full Bayesian inference to explore the accuracy to which LISA can constrain the binary parameters. We demonstrate that LISA will be able to track the evolution of the spins -- magnitude and orientation -- to percent accuracy, providing crucial information on the dynamics and evolution of massive black hole binaries and the galactic environment in which the merger takes place. Such accurate spin-tracking further allows LISA to measure the recoil velocity of the remnant black hole to better than $100\,\mathrm{km}\,\mathrm{s}^{-1}$ (90\% credibility) and its direction to a few degrees, which provides additional important astrophysical information on the post-merger association. Using a systematic suite of binaries, we showcase that the component masses will be measurable at the sub-percent level, the sky area can be constrained to within $\Delta \Omega_{90} \approx 0.01 \, \rm{deg}^2$, and the binary redshift to less than $0.01$.