Mass distribution of ultralight boson in binary black hole systems

TL;DR

This paper explores how ultralight boson clouds around black holes are affected by binary interactions, revealing that mass transfer and spin alignment significantly influence cloud depletion, with implications for gravitational wave detection.

Contribution

It provides a detailed analysis of boson mass transfer dynamics in binary black hole systems with arbitrary spins, highlighting effects of mass ratio and spin orientation.

Findings

Mass ratio impacts boson cloud absorption.

Spin misalignment alters cloud depletion efficiency.

Binary interactions influence potential gravitational wave signals.

Abstract

Ultralight bosons are compelling dark-matter candidates. Both scalar and vector bosons can be produced through black hole superradiance, forming a boson cloud surrounding a rotating black hole. Self-interaction of bosons, together with transition mixing in binary black hole systems, give rise to dynamical phenomena that could be potentially observable with future gravitational wave observations. In this work, we investigate the dynamics of bosons in binary black hole systems. In particular, we focus on boson mass transfer in unequal-mass binary black hole systems with arbitrary spin-orientation of the companion. Our results show that the mass ratio between the companion and the primary black holes significantly affects cloud absorption through mass transfer. Moreover, when the companion's spin is not aligned with that of the primary, the efficiency of cloud depletion is further modified.