Measuring $α$ in the Early Universe: CMB Polarization, Reionization and the Fisher Matrix Analysis

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dc.creatorRocha, G.
dc.creatorTrotta, R.
dc.creatorMartins, C. J. A. P.
dc.creatorMelchiorri, A.
dc.creatorAvelino, P. P.
dc.creatorBean, R.
dc.creatorViana, P. T. P.
dc.date2003-09-08
dc.date.accessioned2026-07-07T11:29:12Z
dc.date.available2026-07-07T11:29:12Z
dc.descriptionWe present a detailed analysis of present and future Cosmic Microwave Background constraints of the value of the fine-structure constant, $α$. We carry out a more detailed analysis of the WMAP first-year data, deriving state-of-the-art constraints on $α$ and discussing various other issues, such as the possible hints for the running of the spectral index. We find, at 95% C.L. that $0.95 < α_{\text{dec}} / α_0 < 1.02$. Setting $dn_S /dlnk=0$, yields $0.94< α_{\text{dec}} / α_0 < 1.01$ as previously reported. We find that a lower value of $α/ α_0$ 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 $α$ and the optical depth $τ$), in order to estimate how future CMB experiments will be able to constrain $α$ and other cosmological parameters. We find that Planck data alone can constrain $τ$ 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 $α$ 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.
dc.description29 pages, 11 figures, 15 tables, submitted to MNRAS. Higher resolution figures available at http://www.mrao.cam.ac.uk/~graca/alpha
dc.identifierhttps://arxiv.org/abs/astro-ph/0309211
dc.identifierhttp://arxiv.org/abs/astro-ph/0309211
dc.identifierMon.Not.Roy.Astron.Soc.352:20,2004
dc.identifierdoi:10.1111/j.1365-2966.2004.07832.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/196638
dc.subjectAstrophysics
dc.titleMeasuring $α$ in the Early Universe: CMB Polarization, Reionization and the Fisher Matrix Analysis
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