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 < α dec/ α 0 < 1.02. Setting dn S/d ln k = 0 yields 0.94 < α dec/α 0 < 1.01 as previously reported. We find that a lower value of α dec/α 0 makes a value of dn S/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.

Measuring α in the early universe: Cosmic microwave background polarization, re-ionization and the Fisher matrix analysis / Rocha, G.; Trotta, R.; Martins, C. J. A. P.; Melchiorri, A.; Avelino, P. P.; Bean, R.; Viana, P. T. P.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 352:1(2004), pp. 20-38. [10.1111/j.1365-2966.2004.07832.x]

Measuring α in the early universe: Cosmic microwave background polarization, re-ionization and the Fisher matrix analysis

Trotta R.;
2004-01-01

Abstract

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 < α dec/ α 0 < 1.02. Setting dn S/d ln k = 0 yields 0.94 < α dec/α 0 < 1.01 as previously reported. We find that a lower value of α dec/α 0 makes a value of dn S/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.
2004
352
1
20
38
Rocha, G.; Trotta, R.; Martins, C. J. A. P.; Melchiorri, A.; Avelino, P. P.; Bean, R.; Viana, P. T. P.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/116859
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