Neutron stars and Pulsar timing arrays as Axion giant gyroscopes

TL;DR

This paper proposes using neutron stars and pulsar timing arrays as giant gyroscopes to detect axion fields, revealing potential constraints on axion-nucleon coupling through pulsar timing residuals.

Contribution

It introduces a novel method to detect axion fields by analyzing neutron star precession and pulsar timing data, linking astrophysical observations to particle physics.

Findings

Current PTA data constrains axion-nucleon coupling to g_{ann} ~ 10^{-12} GeV^{-1}

Neutron star precession modulated by axion wind affects pulsar timing signals

Method provides a new astrophysical probe for axion-like particles

Abstract

We consider the three-dimensional rotating motions of neutron stars blown by the "axion wind". Neutron star precession and spin can change from the magnetic moment coupling to the oscillating axion background field, in analogy to the gyroscope motions with a driving force and the laboratory Nuclear Magnetic Resonance(NMR) detections of the axion. This effect modulates the pulse arrival time of the pulsar timing arrays. It shows up as a signal on the timing residual and two-point correlation function on the recent data of Nanograv and PPTA. The current measurement of PTAs can thus cast constraints on the axion-nucleon coupling as g_{ann} ~ 10^{-12}{GeV}^{-1}.