Searching for axion-like particles under strong gravitational lenses

TL;DR

This paper proposes using strong gravitational lens systems to detect axion-like particles by measuring differential birefringence in polarized light, providing new constraints on ALP-photon coupling within a specific mass range.

Contribution

It introduces a novel method leveraging gravitational lensing and polarization to constrain ALPs, improving detection sensitivity over previous approaches.

Findings

Constrained ALP-photon coupling to between 9.2×10⁻¹¹ and 7.7×10⁻⁸ GeV⁻¹ at 95% confidence.

Applied the method to the lens system CLASS B1152+199, setting new bounds on ALP properties.

Indicated that larger samples could further tighten these constraints.

Abstract

We establish strong gravitational lens systems as robust probes of axion-like particles (ALPs) -- a candidate for dark matter. A tiny interaction of photons with ALPs induces birefringence. Multiple images of gravitationally lensed polarised objects allow differential birefringence measurement, alleviating systematics and astrophysical dependencies. We apply this novel method to the lens system CLASS B1152+199 and constrain ALP-photon coupling $\le 9.2\times 10^{-11}\, {\rm GeV}^{-1} \textrm{ to } 7.7\times 10^{-8}\, {\rm GeV}^{-1}$ ($95\%$ C.L.) for ALP mass between $3.6\times 10^{-21} \,{\rm eV}$ and $4.6 \times 10^{-18} \,{\rm eV}$. A larger sample will improve the constraints.