A search for a contribution from axion-like particles to the X-ray diffuse background utilizing the Earth's magnetic field

Le résumé fourni par la source

The Axion Like Particle (ALP) is a hypothetical pseudo-scalar particle beyond the Standard Model, with a compelling possible connection to dark matter and early universe physics. ALPs can be converted into photons via interactions with magnetic fields in the universe, i.e., the so-called inverse Primakoff effect. In this paper, we propose a novel method to explore ALP-induced photons from X-ray data obtained from the Suzaku satellite, arising from a possible interaction of ALPs with the direction-dependent Earth's magnetic field viewed from the satellite. Suzaku data is suitable for this purpose because its low-altitude Earth orbit result in intrinsically low cosmic-ray background radiation. We study whether the X-ray diffuse background (XDB) spectra estimated from the four deep fields collected over eight years, vary with the integrated Earth's magnetic strength in the direction of each target field at each observation epoch, which amounts to 10 2 Tm—a value greater than that achieved by terrestrial experiments due to the large coherent length. From the detailed analysis, we did not find evidence of the XDB cofidence level spectra having dependence on the Earth's magnetic strength. We obtained 99% confidence level upper limit on a possible residual contribution to the cosmic X-ray background (CXB) surface brightness to be 1.6 × 10 −9 ergs s −1 cm −2 sr −1 normalized at 10 4 T 2 m 2 in the 2–6 keV range, which corresponds to 6–15% of the observed CXB brightness, depending on which model of unresolved point sources are used in the interpretation. It is consistent with 80–90% of the CXB now being resolved into point sources.

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