Search for Axion-Like Particles in High-Magnetic-Field Pulsars with NICER

TL;DR

This study searches for axion-like particles in high-magnetic-field pulsars using NICER X-ray data, setting new constraints on their coupling constants based on spectral analysis.

Contribution

First application of NICER X-ray data to constrain axion-like particles in pulsars through spectral deviation analysis.

Findings

Upper limits on axion-photon coupling constants between 10^{-10} and 10^{-13} GeV^{-1}.

Constraints applicable for ALP masses in the 0.8–10 keV range.

Method demonstrates potential for astrophysical ALP searches using X-ray spectra.

Abstract

Axion-like particles (ALPs) can couple to photons in strong magnetic fields, producing characteristic fluctuations in X-ray spectra. Using data from NASA's Neutron Star Interior Composition Explorer (NICER), we analyzed three pulsars: PSR J2229+6114, PSR J1849-0001, and PSR B0531+21, to search for such features. Each spectrum was modeled with a sliding-window power-law fitting method to identify local deviations from the smooth continuum. From these analyses, we derived constraints on the axion-photon coupling constant $g_{a\gamma\gamma}$ assuming dipole and quadrupole magnetic field distributions. We obtain upper limits in the range $10^{-10}$--$10^{-13}\,\mathrm{GeV}^{-1}$ for ALP masses in the $0.8$--$10~\mathrm{keV}$ region.