Probing Ultralight Bosons with Compact Eccentric Binaries

TL;DR

This paper explores how ultralight bosons forming gravitational atoms around black holes can cause observable effects in gravitational waves and pulsar timing due to large orbital precession in eccentric binaries.

Contribution

It demonstrates that ultralight bosons induce large quadrupole moments and orbital precession, providing a new method to detect these particles through gravitational wave and pulsar timing observations.

Findings

Ultralight bosons create large mass quadrupoles in gravitational atoms.

Eccentric binaries exhibit significant orbital precession.

Observable signatures appear in gravitational wave and pulsar timing data.

Abstract

Ultralight bosons can be abundantly produced through superradiance process by a spinning black hole and form a bound state with hydrogen-like spectrum. We show that such a "gravitational atom" typically possesses anomalously large mass quadrupole and leads to significant orbital precession when it forms an eccentric binary with a second compact object. Dynamically formed black hole binaries or pulsar-black hole binaries are typically eccentric during their early inspirals. We show that the large orbital precession can generate distinct and observable signature in their gravitational wave or pulsar timing signals.