SMALL-SCALE MICROWAVE BACKGROUND FLUCTUATIONS FROM COSMIC STRINGS

The cosmic microwave background (CMB) fluctuations at very small angul ar scales (less than 10') induced by matter sources are computed in a simplified way. The result corrects a previous formula appearing in th e literature. The small-scale power spectrum from cosmic strings is th en calculated by a new analytic method. The result compares extremely well with the spectrum computed by numerical techniques (when the old, incorrect, formula is used). The upper bound on the string parameters derived from OVRO data is reexamined, taking into account the non-Gau ssian nature of stringy perturbations on small scales. Assuming a conv entional ionization history, the-bound is gammaGmu < 11 x 10(-6), wher e gamma2 is the number of horizontal lengths of string per horizontal volume. Current simulations give gamma2 = 31 +/- 7.