Cosmic Microwave Background Anisotropy Induced by Cosmic Strings on Angular Scales≳15′

We have computed an estimate of the angular power spectrum of the cosmic microwave background induced by cosmic strings on angular scales $\gtrsim {15}^{\prime }$, using a numerical simulation of a cosmic string network and have decomposed this pattern into scalar, vector, and tensor parts. The anisotropies from vector modes dominate except on very small angular scales, and we find no evidence for strong acoustic oscillations in the scalar anisotropy. The anisotropies generated after recombination are even more important than in adiabatic models. The total anisotropy on small scales is inconsistent with current measurements. The calculation has a number of uncertainties, the largest of which is due to finite temporal range.