Analytical model for CMB temperature angular power spectrum from cosmic (super-)strings

TL;DR

This paper introduces an analytical model for the CMB temperature power spectrum caused by cosmic (super-)strings, highlighting the dependence on intercommuting probability and providing constraints on string tension.

Contribution

The authors develop a new analytical approach to calculate the small-angle CMB spectrum from cosmic strings, including the effects of varying intercommuting probabilities, and compare results with numerical simulations.

Findings

Power spectrum dominated by Poisson-distributed string segments.

Spectrum shows a plateau on large scales and a power-law decline on small scales.

Tighter constraints on string tension for smaller intercommuting probabilities.

Abstract

We present a new analytical method to calculate the small angle CMB temperature angular power spectrum due to cosmic (super-)string segments. In particular, using our method, we clarify the dependence on the intercommuting probability $P$. We find that the power spectrum is dominated by Poisson-distributed string segments. The power spectrum for a general value of $P$ has a plateau on large angular scales and shows a power-law decrease on small angular scales. The resulting spectrum in the case of conventional cosmic strings is in very good agreement with the numerical result obtained by Fraisse et al.. Then we estimate the upper bound on the dimensionless tension of the string for various values of $P$ by assuming that the fraction of the CMB power spectrum due to cosmic (super-)strings is less than ten percents at various angular scales up to $\ell=2000$. We find that the amplitude of the spectrum increases as the intercommuting probability. As a consequence, strings with smaller intercommuting probabilities are found to be more tightly constrained.