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arXiv · 1509.06748

Galaxy Cluster Thermal X-Ray Spectra Constrain Axion-Like Particles

Joseph P. Conlon·M. C. David Marsh·Andrew J. Powell
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Abstract

Axion-like particles (ALPs) and photons inter-convert in the presence of a magnetic field. At keV energies in the environment of galaxy clusters, the conversion probability can become unsuppressed for light ALPs. Conversion of thermal X-ray photons into ALPs can introduce a step-like feature into the cluster thermal bremsstrahlung spectrum, and we argue that existing X-ray data on galaxy clusters should be sufficient to extend bounds on ALPs in the low-mass region $m_a \lesssim 1 \times 10^{-12}\,{\rm eV}$ down to $M \sim 7\times 10^{11}\, {\rm GeV}$, and that for $10^{11}\, {\rm GeV} < M \lesssim 10^{12}$ GeV light ALPs give rise to interesting and unique observational signatures that may be probed by existing and upcoming X-ray (and potentially X-ray polarisation) observations of galaxy clusters.

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Joseph P. Conlon, M. C. David Marsh, Andrew J. Powell. 2015-09-22. Galaxy Cluster Thermal X-Ray Spectra Constrain Axion-Like Particles. https://doi.org/10.1103/physrevd.93.123526

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