Constraints on Axion-Like Particles from X-ray Observations of NGC1275

TL;DR

This study uses high-quality X-ray data from NGC1275 to search for axion-like particles, setting new constraints on their properties by analyzing spectral irregularities caused by ALP-photon interactions.

Contribution

The paper provides the first constraints on ALP-photon coupling using deep X-ray observations of NGC1275, improving existing bounds in the low-mass regime.

Findings

No spectral irregularities detected at 30% level

Constraints on ALP-photon coupling: g_{aγγ} ≲ 1.4-4.0 × 10^{-12} GeV^{-1}

Limits apply for ALP masses m_a ≲ 10^{-12} eV

Abstract

Axion-like particles (ALPs) can induce localised oscillatory modulations in the spectra of photon sources passing through astrophysical magnetic fields. Ultra-deep Chandra observations of the Perseus cluster contain over $5 \times 10^5$ counts from the AGN of the central cluster galaxy NGC1275, and represent a dataset of extraordinary quality for ALP searches. We use this dataset to search for X-ray spectral irregularities from the AGN. The absence of irregularities at the O(30%) level allows us to place leading constraints on the ALP-photon mixing parameter $g_{a\gamma\gamma} \lesssim 1.4 - 4.0 \times 10^{-12} {\rm GeV}^{-1}$ for $m_a \lesssim 10^{-12}$ eV, depending on assumptions on the magnetic field realisation along the line of sight.