Updated Bounds on Axion-Like Particles from X-ray Observations

Abstract

In this work we revisit five different point sources within or behind galaxy clusters in order to constrain the coupling constant between axion-like particles (ALPs) and photons. We use three distinct machine learning (ML) techniques and compare our results with a standard ${\chi }^2$ analysis. For the first time we apply approximate Bayesian computation to searches for ALPs and find consistently good performance across ML classifiers. Further, we apply more realistic 3D magnetic field simulations of galaxy clusters and compare our results with previously used 1D simulations. We find constraints on the ALP-photon coupling at the level of state-of-the-art bounds with $g_{a\gamma \gamma }\lesssim 0.6\times 10^{-12}$ GeV${}^{-1}$, hence improving on previous constraints obtained from the same observations.

v2: minor changes, 14 pages, 7 figures, 11 tables; matches accepted version to appear in MNRAS

References in corpus (2)

• Projected bounds on ALPs from Athena
• The Fourier formalism for relativistic axion-photon conversion, with astrophysical applications

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• Photon-ALP oscillations inducing modifications to photon polarization
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• Physics Beyond the Standard Model with Future X-ray Observatories: Projected Constraints on Very-Light Axion-Like Particles with $Athena$ and $AXIS$
• Revisiting the evidences for spectral anomalies in distant blazars: new data on the photon-ALP mixing