Fitting cosmic microwave background data with cosmic strings and inflation

We perform a multiparameter likelihood analysis to compare measurements of the cosmic microwave background (CMB) power spectra with predictions from models involving cosmic strings. Adding strings to the standard case of a primordial spectrum with power-law tilt n(s), we find a 2 sigma detection of strings: f(10)=0.11 +/- 0.05, where f(10) is the fractional contribution made by strings in the temperature power spectrum (at l =10). CMB data give moderate preference to the model n(s)=1 with cosmic strings over the standard zero-strings model with variable tilt. When additional non-CMB data are incorporated, the two models become on a par. With variable n(s) and these extra data, we find that f(10)< 0.11, which corresponds to G(mu)< 0.7x10(-6) (where mu is the string tension and G is the gravitational constant).