# Effect of radiation-like solid on small-scale CMB anisotropies

## TL;DR

This paper investigates how a radiation-like solid with shear modulus influences small-scale cosmic microwave background anisotropies, revealing observable effects under certain conditions.

## Contribution

It introduces the concept of a radiation-like solid affecting CMB anisotropies and computes its impact on the angular power spectrum.

## Key findings

- Solid affects small-scale anisotropies within cosmic variance limits
- Observable effects occur for shear modulus values close to zero
- Potential to distinguish solid effects in future CMB observations

## Abstract

We compute the CMB angular power spectrum in the presence of a radiation-like solid - elastic matter with the same pressure to energy density ratio as radiation but with nonzero shear modulus. For the values of shear modulus that are close enough to zero, so that the effect of the solid on large-scale anisotropies remains within cosmic variance, we find that there is an observable effect of the solid on small-scale anisotropies.