Constraints on the variation of fine structure constant from joint SPT-SZ and XMM-Newton observations

Bora, K. and Desai, Shantanu (2021) Constraints on the variation of fine structure constant from joint SPT-SZ and XMM-Newton observations. Journal of Cosmology and Astroparticle Physics, 2021 (012). ISSN 14757516

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Abstract

We search for a variation of the electromagnetic fine structure constant (α ≡ e2/ c) using a sample of 58 SZ selected clusters in the redshift range (0.2<z<1.5) detected by the South Pole Telescope, along with X-ray measurements using the XMM-Newton observatory. We use the ratio of the integrated SZ Compto-ionization to its X-ray counterpart as our observable for this search. We first obtain a model-independent constraint on α of about 0.7%, using the fact that the aforementioned ratio is constant as function of redshift. We then look for logarithmic dependence of α as a function of redshift: Δ α/α = -γ (1+z), as this is predicted by runaway dilaton models. We find that γ = -0.046 ± 0.1, which indicates that there is no logarithmic variation of α as a function redshift. We also search for a dipole variation of the fine structure constant using the same cluster sample. We do not find any evidence for such a spatial variation.

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