Early structure formation from cosmic string loops

TL;DR

This paper investigates how cosmic string loops could influence early universe structure formation and reionization, highlighting their potential detectability via CMB observations and their role in addressing standard galaxy formation issues.

Contribution

The study advances previous models by incorporating high loop velocities and filamentary halo shapes, providing more accurate predictions of cosmic string effects on early structure formation.

Findings

Cosmic strings with Gμ > 10^{-7} significantly affect CMB spectra.

Strings could induce early star formation and reionization.

Potential to detect cosmic string signatures with Planck satellite data.

Abstract

We examine the effects of cosmic strings on structure formation and on the ionization history of the universe. While Gaussian perturbations from inflation are known to provide the dominant contribution to the large scale structure of the universe, density perturbations due to strings are highly non-Gaussian and can produce nonlinear structures at very early times. This could lead to early star formation and reionization of the universe. We improve on earlier studies of these effects by accounting for high loop velocities and for the filamentary shape of the resulting halos. We find that for string energy scales G\mu > 10^{-7} the effect of strings on the CMB temperature and polarization power spectra can be significant and is likely to be detectable by the Planck satellite. We mention shortcomings of the standard cosmological model of galaxy formation which may be remedied with the addition of cosmic strings, and comment on other possible observational implications of early structure formation by strings.