CMB constraints on cosmic strings and superstrings

TL;DR

This paper performs a comprehensive MCMC analysis of cosmological models with cosmic strings and superstrings, providing updated constraints on string tensions and network parameters using Planck data.

Contribution

It introduces the first complete MCMC analysis of evolving cosmic (super)string networks with new constraints on string tensions and network parameters.

Findings

Updated constraint on cosmic string tension: Gmu<1.1x10^-7

Constraint on superstring tension: Gmu_F<2.8x10^-8

Most comprehensive CMB analysis of strings in LambdaCDM to date

Abstract

We present the first complete Markov chain Monte Carlo analysis of cosmological models with evolving cosmic (super)string networks, using the unconnected segment model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on Lambda cold dark matter (CDM) and string network parameters, namely the string tension Gmu, the loop-chopping efficiency c_r and the string wiggliness \alpha. For cosmic superstrings, we obtain joint constraints on the fundamental string tension Gmu_F, the string coupling g_s, the self-interaction coefficient c_s, and the volume of compact extra dimensions w. This constitutes the most comprehensive CMB analysis of LambdaCDM cosmology + strings to date. For ordinary cosmic string networks our updated constraint on the string tension is, in relativistic units, Gmu<1.1x10^-7, while for cosmic superstrings our constraint on the fundamental string tension is Gmu_F<2.8x10^-8, both obtained using Planck2015 temperature and polarisation data.