Cosmic strings confront COBE

We investigate large-angle anisotropies in the cosmic microwave radiation background which are induced by cosmic strings. We numerically evolve a string network from a redshift Z=100 to the present day and we use this data to generate a full-sky temperature map using sophisticated Green's function methods. Based on a limited number of realizations, we have compared the results of our simulations with the observations of the COBE-DMR experiment, demonstrating broad consistency. We have obtained a preliminary normalization for the string mass-per-unit-length # in the cosmic string scenario. 1 I n t r o d u c t i o n Cosmic strings are relics from a hot dense phase of the early universe [1]. They have been invoked to solve a variety of cosmological enigmas, including the origin of the primordial perturbations necessary to seed galaxy formation [2]. Their properties and cosmological implications have been actively investigated for some considerable time [3]. The understanding of the effects of superheavy cosmic strings in an expanding universe can be summarized as follows: On large scales close to the horizon size, long wiggly strings sweep out wakes in the cosmological fluid, leaving overdense regions which may grow to form galaxies and clusters [4,5]. On small scales, small loops are chopped off and ejected from the long strings. These loops then contract and expand under their own tension, radiating gravitational waves [6,7]. Processes on both large and small scales contribute to the gross features of the cosmic string scenario and the associated observational signatures. It is important to note that the understanding of the cosmological implications of strings has undergone some evolution, however,