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Measuring $alpha$ in the Early Universe: CMB Polarization, Reionization and the Fisher Matrix Analysis | | G. Rocha
; R. Trotta
; C.J.A.P. Martins
; A. Melchiorri
; P.P. Avelino
; R. Bean
; P.T.P. Viana
; | | Date: |
8 Sep 2003 | | Journal: | Mon.Not.Roy.Astron.Soc. 352 (2004) 20 | | Subject: | astro-ph | | Affiliation: | Cambridge, CAUP), R. Trotta (Geneva), C.J.A.P. Martins (CAUP, Cambridge, IAP), A. Melchiorri (Oxford, Roma), P.P. Avelino (Porto), R. Bean (Princeton), P.T.P. Viana (CAUP | | Abstract: | We present a detailed analysis of present and future Cosmic Microwave Background constraints of the value of the fine-structure constant, $alpha$. We carry out a more detailed analysis of the WMAP first-year data, deriving state-of-the-art constraints on $alpha$ and discussing various other issues, such as the possible hints for the running of the spectral index. We find, at 95% C.L. that $0.95 < alpha_{ ext{dec}} / alpha_0 < 1.02$. Setting $dn_S /dlnk=0$, yields $0.94< alpha_{ ext{dec}} / alpha_0 < 1.01$ as previously reported. We find that a lower value of $alpha / alpha_0$ makes a value of $d n_S /dlnk = 0$ more compatible with the data. We also perform a thorough Fisher Matrix Analysis (including both temperature and polarization, as well as $alpha$ and the optical depth $ au$), in order to estimate how future CMB experiments will be able to constrain $alpha$ and other cosmological parameters. We find that Planck data alone can constrain $ au$ with a accuracy of the order 4% and that this constraint can be as small as 1.7% for an ideal cosmic variance limited experiment. Constraints on $alpha$ are of the order 0.3% for Planck and can in principle be as small as 0.1% using CMB data alone - tighter constraints will require further (non-CMB) priors. | | Source: | arXiv, astro-ph/0309211 | | Services: | Forum | Review | PDF | Favorites | |
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