# Fitting CMB data with cosmic strings and inflation

Bevis, Neil, Hindmarsh, Mark, Kunz, Martin and Urrestilla, Jon (2008) Fitting CMB data with cosmic strings and inflation. Physical Review Letters, 100 (2). 021301. ISSN 0031-9007

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We perform a multi-parameter likelihood analysis to compare measurements of the cosmic microwave background (CMB) power spectra with predictions from models involving cosmic strings. We explore the addition of strings to the inflationary concordance model, involving an adiabatic primordial power spectrum with a power-law tilt n, as well as the Harrison-Zeldovich (HZ) case n=1. Using ACBAR, BOOMERANG, CBI, VSA and WMAP data we show that of the models investigated, the HZ case with strings provides the best fit to the data relative to the freedom in the model, having a moderately higher Bayesian evidence than the concordance model. For HZ plus strings, CMB data then implies a (10+/-3)% string contribution to the temperature power spectrum at multipole l=10. However, with non-CMB data included, finite tilt and finite strings are approximately on par with each other. Considering variable $\\\\ns$, we then find a 95% upper limit of the string fraction of 11%, corresponding to \$G\\\\mu