Effect of radiation-like solid on CMB anisotropies

TL;DR

This paper investigates how a radiation-like solid with shear modulus influences the cosmic microwave background's anisotropies, affecting both large and small angular scales.

Contribution

It provides a detailed calculation of the CMB power spectrum considering a radiation-like solid, extending previous work to include small-angle anisotropies.

Findings

Radiation-like solid impacts CMB anisotropies at all angular scales.

Effects are observable beyond large angles, including very small angles.

The presence of shear modulus modifies the angular power spectrum significantly.

Abstract

We compute the CMB angular power spectrum in the presence of the radiation-like solid with the same pressure to energy density ratio as for the radiation but with nonzero shear modulus. The effect can be observable not only for large-angle anisotropies as shown by Balek and \v{S}kovran [2015] but also for very small-angle ones.