Non-parametric reconstruction of the fine structure constant with galaxy clusters

Abstract

Testing possible variations in fundamental constants of nature is a crucial endeavor in observational cosmology. This paper investigates potential cosmological variations in the fine structure constant (\(\alpha \)) through a non-parametric approach, using galaxy cluster observations as the primary cosmological probe. We employ two methodologies based on galaxy cluster gas mass fraction measurements derived from X-ray and Sunyaev–Zeldovich observations, along with luminosity distances from type Ia supernovae. We also explore how different values of the Hubble constant (\(H_0\)) impact the variation of \(\alpha \) across cosmic history. When using the Planck satellite’s \(H_0\) observations, a constant \(\alpha \) is ruled out at approximately the 3\(\sigma \) confidence level for \(z \lesssim 0.5\). Conversely, employing local estimates of \(H_0\) restores agreement with a constant \(\alpha \).