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

This paper presents the constraints on the time variation of the fine structure constant at recombination relative to its present value, Δα = (αrec − α0)/α0, 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 < Δα < 0.010 at 95% CL, which brings a 30% improvement to the previous limits from WMAP-1yr data. The corresponding recombination redshift, zrec=1075-63+40, shows a delayed recombination epoch compared with the results from WMAP-1yr data.