New constraints on varying α
Abstract
We present a summary of recent constraints on the value of the finestructure constant at the epoch of decoupling from the recent observations made by the Wilkinson microwave anisotropy probe (WMAP) satellite. Within the set of models considered, a variation of the value of α at decoupling with respect to the presentday value is now bounded to be smaller than 2% (6%) at 95% confidence level. We point out that the existence of an early reionization epoch as suggested by the above measurements will, when more accurate cosmic microwave background polarization data are available, lead to considerably tighter constraints. We find that the tightest possible constraint on α is about 0.1% using CMB data alone  tighter constraints will require further (nonCMB) priors.
 Publication:

New Astronomy Reviews
 Pub Date:
 November 2003
 DOI:
 10.1016/j.newar.2003.07.018
 arXiv:
 arXiv:astroph/0309205
 Bibcode:
 2003NewAR..47..863R
 Keywords:

 Astrophysics
 EPrint:
 6 pages, 4 figures, 3 tables, to appear in New Astronomy Reviews, Proceedings of the 2nd CMBNET workshop, 2021 February 2003, Oxford, UK