Reconstructing the temporal evolution of the speed of light in a flat FRW Universe

Abstract

We present a novel method to reconstruct the temporal evolution of the speed of light c(z) in a flat Friedmann-Robertson-Walker (FRW) Universe using astronomical observations. After validating our pipeline with mock datasets, we apply our method to the latest baryon acoustic oscillations (BAO) and supernovae observations, and reconstruct c(z) in the redshift range of z ∈ [0, 1.5]. We find no evidence of a varying speed of light, although we see some interesting features of ∆c(z), the fractional difference between c(z) and c₀ (the speed of light in the International System of Units), e.g., ∆c(z) < 0 and ∆c(z) > 0 at 0.2⪅z⪅0.5 and 0.8⪅z⪅1.3, respectively, although the significance of these features is currently far below statistical importance.