Imprints of ultralight axions on the gravitational wave and pulsar timing measurement

TL;DR

This paper explores how ultralight axion-like particles could influence gravitational wave signals and pulsar timing, proposing observational signatures detectable by space-based detectors and radio telescopes, and comparing these effects with other dark matter interactions.

Contribution

It introduces new potential observational effects of ultralight axions on gravitational waves and pulsar timing, and assesses their detectability with upcoming space-based detectors.

Findings

Axion clouds around black holes can modify gravitational waveforms.

The effects are comparable to dynamical friction and dipole radiation.

Constraints from LIGO/Virgo and prospects for LISA and TianQin are discussed.

Abstract

The axion or axion-like particle motivated from a natural solution of strong CP problem or string theory is a promising dark matter candidate. We study the new observational effects of ultralight axion-like particles by the space-borne gravitational wave detector and the radio telescope. Taking the neutron star-black hole binary as an example, we demonstrate that the gravitational waveform could be obviously modified by the slow depletion of the axion cloud around the black hole formed through the superradiance process. We compare these new effects on the binary with the well-studied effects from dynamical friction with dark matter and dipole radiation in model-independent ways. Finally, we discuss the constraints from LIGO/Virgo and study the detectability of the ultralight axion particles at LISA and TianQin.