Delayed recombination and standard rulers
- Universita' di Roma 'La Sapienza', Ple Aldo Moro 2, 00185, Rome (Italy)
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, New York 14853 (United States)
- Universita di Roma 'La Sapienza', Ple Aldo Moro 2, 00185, Rome (Italy)
- Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, OX1 3RH, Oxford (United Kingdom)
- Institute of Space Sciences (IEEC-CSIC), Facultat Ciencies, Campus UAB, Bellaterra (Spain)
Measurements of baryonic acoustic oscillations (BAOs) in galaxy surveys have been recognized as a powerful tool for constraining dark energy. However, this method relies on the knowledge of the size of the acoustic horizon at recombination derived from cosmic microwave background (CMB) anisotropy measurements. This estimate is typically derived assuming a standard recombination scheme; additional radiation sources can delay recombination altering the cosmic ionization history and the cosmological inferences drawn from CMB and BAO data. In this paper we quantify the effect of delayed recombination on the determination of dark energy parameters from future BAO surveys such as the Baryon Oscillation Spectroscopic Survey and the Wide-Field Multi-Object Spectrograph. We find the impact to be small but still not negligible. In particular, if recombination is nonstandard (to a level still allowed by CMB data), but this is ignored, future surveys may incorrectly suggest the presence of a redshift-dependent dark energy component. On the other hand, in the case of delayed recombination, adding to the analysis one extra parameter describing deviations from standard recombination does not significantly degrade the error bars on dark energy parameters and yields unbiased estimates. This is due to the CMB-BAO complementarity.
- OSTI ID:
- 21259986
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 79, Issue 4; Other Information: DOI: 10.1103/PhysRevD.79.043503; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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