PhysRevD.70.043508.pdf (148.41 kB)
WMAP constraints on inflationary models with global defects
journal contributionposted on 2023-06-07, 22:38 authored by Neil Bevis, Mark HindmarshMark Hindmarsh, Martin Kunz
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).
- Published version
JournalPhysical Review D
Department affiliated with
- Physics and Astronomy Publications
NotesCollaboration leader and supervisor of research student Bevis and PDRA Kunz. The first assessment of cosmological models with cosmic texture with then-current CMB (Cosmic Microwave Background) data. At most 13% of CMB fluctuations at large angular scales could be attributed to cosmic texture.
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