Cosmic string parameter constraints and model analysis using small scale Cosmic Microwave Background data

TL;DR

This paper updates constraints on Abelian Higgs cosmic string tension using recent high-resolution CMB data, showing tighter bounds and disfavoring a scale-invariant spectrum, with no preference for cosmic strings.

Contribution

It provides improved predictions for cosmic string effects on CMB spectra and tighter observational bounds using new data and simulations.

Findings

Bounds on string contribution: f10< 0.095 (WMAP7) and f10< 0.048 (all data)

Bounds on string tension: Gμ< 0.57×10^-6 (WMAP7) and Gμ< 0.42×10^-6 (all data)

Disfavoring of ns=1 spectrum at 2.4σ with all data

Abstract

We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the latest results of the WMAP satellite, and by improved predictions for the impact of Abelian Higgs cosmic strings on the CMB power spectra. The new cosmic string spectra (presented in a previous work) were improved especially for small angular scales, through the use of larger Abelian Higgs string simulations and careful extrapolation. If Abelian Higgs strings are present then we find improved bounds on their contribution to the CMB anisotropies, f10< 0.095, and on their tension, G\mu< 0.57 x 10^-6, both at 95% confidence level using WMAP7 data; and f10 < 0.048 and G\mu < 0.42 x 10^-6 using all the CMB data. We also find that using all the CMB data, a scale invariant initial perturbation spectrum, ns=1, is now disfavoured at 2.4\sigma\ even if strings are present. A Bayesian model selection analysis no longer indicates a preference for strings.