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

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.