WMAP constraints on inflationary models with global defects

Hindmarsh, M.B.H., Bevis, N. and Kunz, M. (2004) WMAP constraints on inflationary models with global defects. Physical Review D, 70 (4). 043508. ISSN 0556-2821

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We use the cosmic microwave background angular power spectra to place upper limits on the degree to which global defects may have aided cosmic structure formation. We explore this under the inflationary paradigm, but with the addition of textures resulting from the breaking of a global O(4) symmetry during the early stages of the Universe. As a measure of their contribution, we use the fraction of the temperature power spectrum that is attributed to the defects at a multipole of 10. However, we find a parameter degeneracy enabling a fit to the first-year WMAP data to be made even with a significant defect fraction. This degeneracy involves the baryon fraction and the Hubble constant, plus the normalization and tilt of the primordial power spectrum. Hence, constraints on these cosmological parameters are weakened. Combining the WMAP data with a constraint on the physical baryon fraction from big bang nucleosynthesis calculations and high-redshift deuterium abundance limits the extent of the degeneracy and gives an upper bound on the defect fraction of 0.13 (95% confidence).

Item Type: Article
Keywords: radiofrequency cosmic radiation; cosmology; spontaneous symmetry breaking; nucleosynthesis
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics
Depositing User: Gemma Farrell
Date Deposited: 14 Mar 2008
Last Modified: 07 Mar 2017 05:55
URI: http://srodev.sussex.ac.uk/id/eprint/1634
Google Scholar:56 Citations

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