Large Angular Scale Anisotropy in Cosmic Microwave Background Induced by Cosmic Strings

We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on 192 maps, we compute the anisotropy power spectrum for multipole moments $\ell \le 20$. By comparing with the observed temperature anisotropy, we set the normalization for the cosmic string mass per unit length $\mu$, obtaining $G\mu {/c}^2{=1.05\mathrm{}}_{-0.20\mathrm{}}^{+0.35\mathrm{}}\times {10}^{-6\mathrm{}}$, which is consistent with all other observational constraints on cosmic strings. We demonstrate that the anisotropy pattern is consistent with a Gaussian random field on large angular scales.