Fitting CMB data with cosmic strings and inflation

This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available. Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. 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 detection of strings: f 10 ˆ 0:11 0:05, where f 10 is the fractional contribution made by strings in the temperature power spectrum (at ' ˆ 10). CMB data give moderate preference to the model n s ˆ 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 < 0:7 10 ÿ6 (where is the string tension and G is the gravitational constant). Introduction.—The inflationary paradigm is successful in providing a match to measurements of the cosmic microwave background (CMB) radiation, and it appears that any successful theory of high energy physics must be able to incorporate inflation. While ad hoc single-field inflation can provide a match to the data, more theoretically motivated models commonly predict the existence of cosmic strings [1]. These strings are prevalent in supersymmetric D-and F-term hybrid inflation models (see, e.g., [2]) and occur frequently in grand-unified theories [3]. String theory can also yield strings of cosmic extent [4]. Hence the observational consequences of cosmic strings are important …