Constraints on time variation of fine structure constant from WMAP-3yr data

TL;DR

This study uses WMAP-3yr data combined with HST priors to constrain the variation of the fine structure constant over cosmic time, improving previous limits and indicating a slightly delayed recombination epoch.

Contribution

It provides tighter constraints on the time variation of the fine structure constant using WMAP-3yr data and HST priors, refining previous bounds and implications for recombination history.

Findings

Delta_alpha constrained to -0.039 < Delta_alpha < 0.010 at 95% C.L.

Recombination redshift estimated between 1012 and 1115.

Results indicate a delayed recombination epoch compared to earlier data.

Abstract

This paper presents the constraints on the time variation of the fine structure constant at recombination relative to its present value, Delta_alpha = (alpha_rec-alpha_0) / alpha_0, obtained from the analysis of the WMAP-3yr Cosmic Microwave Background (CMB) data, with an additional prior on the Hubble expansion rate from HST Hubble Key Project. I found out that -0.039 < Delta_alpha < 0.010 at 95% C.L., which brings a 30% improvement to the previous limits from WMAP-1yr data. The corresponding recombination redshift, 1012 < z_rec < 1115, shows a delayed recombination epoch compared with the results from WMAP-1yr data.