Scientific article
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Measuring α in the early Universe: cosmic microwave background polarization, re-ionization and the Fisher matrix analysis

Published inMonthly notices of the Royal Astronomical Society, vol. 352, no. 1, p. 20-38
Publication date2004-07

We present a detailed analysis of present and future cosmic microwave background (CMB) 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 per cent confidence level, that 0.95 < αdec0 < 1.02. Setting dnS/d ln k= 0 yields 0.94 < αdec0 < 1.01 as previously reported. We find that a lower value of αdec0 makes a value of dnS/d ln k= 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 an accuracy of the order 4 per cent and that this constraint can be as small as 1.7 per cent for an ideal cosmic variance limited (CVL) experiment. Constraints on α are of the order of 0.3 per cent for Planck and can in principle be as small as 0.1 per cent using CMB data alone: tighter constraints will require further (non-CMB) priors.

  • Cosmic microwave background
  • Cosmological parameters
  • Cosmology: miscellaneous
  • Cosmology: observations
  • Cosmology: theory
  • Large-scale structure of Universe
Citation (ISO format)
ROCHA, G. et al. Measuring <i>α </i>in the early Universe: cosmic microwave background polarization, re-ionization and the Fisher matrix analysis. In: Monthly notices of the Royal Astronomical Society, 2004, vol. 352, n° 1, p. 20–38. doi: 10.1111/j.1365-2966.2004.07832.x
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Article (Published version)
ISSN of the journal0035-8711

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