Bounds on Cosmic Strings from WMAP and SDSS

Abstract

We find the constraints from WMAP and SDSS data on the fraction of cosmological fluctuations sourced by local cosmic strings using a Markov Chain Monte Carlo (MCMC) analysis. In addition to varying the usual 6 cosmological parameters and the string tension ($\mu$), we also varied the amount of small-scale structure on the strings. Our results indicate that cosmic strings can account for up to 7 (14)% of the total power of the microwave anisotropy at 68 (95)% confidence level. The corresponding bound on the string mass per unit length, within our string model, is $G\mu < 1.8 (2.7) \times 10^{-7}$ at 68 (95)% c.l., where this constraint has been altered from what appears below following the correction of errors in our cosmic string code outlined in a recent erratum, astro-ph/0604141. We also calculate the B-type polarization spectra sourced by cosmic strings and discuss the prospects of their detection.