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Cosmic microwave anisotropies from BPS semilocal strings
journal contribution
posted on 2023-06-07, 19:12 authored by Jon Urrestilla, Neil Bevis, Mark HindmarshMark Hindmarsh, Martin Kunz, Andrew LiddleWe present the first ever calculation of cosmic microwave background (CMB) anisotropy power spectra from semilocal cosmic strings, obtained via simulations of a classical field theory. Semilocal strings are a type of non-topological defect arising in some models of inflation motivated by fundamental physics, and are thought to relax the constraints on the symmetry breaking scale as compared to models with (topological) cosmic strings. We derive constraints on the model parameters, including the string tension parameter mu, from fits to cosmological data, and find that in this regard Bogomol'nyi-Prasad -Sommerfield (BPS) semilocal strings resemble global textures more than topological strings. The observed microwave anisotropy at l = 10 is reproduced if mu = 5.3 x 10(-6) (G is Newton's constant). However as with other defects the spectral shape does not match observations, and in models with inflationary perturbations plus semilocal strings the 95% confidence level upper bound is G mu < 2.0 x 10(-6) when CMB, Hubble key project and big bang nucleosynthesis data are used (cf G mu < 0.9 x 10(-6) for cosmic strings). We additionally carry out a Bayesian model comparison of several models with and without defects, showing that models with defects are neither conclusively favoured nor disfavoured at present.
History
Publication status
- Published
Journal
Journal of Cosmology and Astroparticle PhysicsISSN
1475-7516External DOI
Issue
7Volume
2008Page range
1-26Department affiliated with
- Physics and Astronomy Publications
Notes
Article Number: 010Full text available
- No
Peer reviewed?
- Yes