Cosmic strings and the microwave sky. I - Anisotropy from moving strings

In this paper we develop a method for calculating the component of the microwave anisotropy around cosmic string loops due to their rapidly changing gravitational fields. The method is only valid for impact parameters from the string much smaller than the horizon size at the time the photon passes the string. The methods developed allows one to calculate the temperature pattern around arbitrary string configurations numerically in terms of one-dimensional integrals. This method is applied to temperature jump across a string, confirming and extending previous work. It is also applied to cusps and kinks on strings, and to determining the temperature pattern far from a strong loop. The temperature pattern around a few loop configurations is explicitly calculated. The fractional temperature deviation near the string is typically 5-10Gμ/c^2^. Very large anisotropies are produced near cusps and kinks. These large anisotropies only occur over a relatively small angular area on the sky. Comparisons with the work of Brandenberger, Albrecht, and Turok indicates that they have overestimated the MBR anisotropy from gravitational radiation emitted from loops.