Measuring α in the early universe: CMB temperature, large-scale structure, and Fisher matrix analysis

C. J. A. P. Martins, A. Melchiorri, R. Trotta, R. Bean, G. Rocha, P. P. Avelino, P. T. P. Viana

Abstract
We extend our recent work on the effects of a time-varying fine-structure constant α in the cosmic microwave background by providing a thorough analysis of the degeneracies between α and the other cosmological parameters, and discussing ways to break these with both existing and/or forthcoming data. In particular, we present the state-of-the-art cosmic microwave background constraints on α through a combined analysis of the BOOMERanG, MAXIMA and DASI data sets. We also present a novel discussion of the constraints on α coming from large-scale structure observations, focusing in particular on the power spectrum from the 2dF survey. Our results are consistent with no variation in α from the epoch of recombination to the present day, and restrict any such variation to be less than about 4%. We show that the forthcoming Microwave Anisotropy Probe and Planck experiments will be able to break most of the currently existing degeneracies between α and other parameters, and measure α to better than percent accuracy.

Physical Review D
Volume 66, Page 023505
June 2002