Hints of Isocurvature Perturbations in the Cosmic Microwave Background
نویسندگان
چکیده
The improved data on the cosmic microwave background (CMB) anisotropy allows a better determination of the adiabaticity of the primordial perturbation. Interestingly, we find that the CMB favors a significant contribution of a primordial isocurvature mode where the entropy perturbation is positively correlated with the primordial curvature perturbation and has a large spectral index (niso ∼ 3). With 4 additional parameters we obtain a better fit to the CMB data by ∆χ 2 = 9.6 compared to an adiabatic model. At more than 95% C.L., the nonadiabatic contribution to the CMB temperature variance is nonzero; indeed positive. For the best-fit model it is 4%.
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