Cosmic strings as the source of small-scale microwave background anisotropy

Abstract

Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (ℓ < 1000) and is bounded to contribute no more than 10%of the total power on those scales. However, when this bound is marginally saturated, the anisotropy created by cosmic strings on small angular scalesℓ ≳ 2000 will dominate over that created by the primary inflationaryperturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.