Photon-ALP interaction as a measure of initial photon polarization

TL;DR

This paper establishes a theoretical relationship between initial photon polarization and photon-ALP conversion probability, enabling astrophysical observations to infer properties of axion-like particles and their interactions.

Contribution

It presents new theorems linking photon polarization to ALP conversion, providing a novel method to use flux measurements as polarimeters for ALP detection.

Findings

Derived strict theorems relating polarization and ALP conversion

Proposed a method to use astrophysical spectra as polarimeters

Enhanced the potential for astrophysical detection of ALPs

Abstract

Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by superstring theory. ALPs interact primarily with two photons and in the presence of an external magnetic field they generate photon-ALP oscillations and the change of the polarization state of photons. While well motivated from a theoretical point of view, hints on ALP existence come from astrophysics. In this paper, we state and demonstrate some theorems about a strict relationship between initial photon polarization and photon-ALP conversion probability - which can be extrapolated by observed astrophysical spectra - so that, in the presence of ALPs, flux-measuring observatories become also porarimeters.