2006/11/30 by Reijo Keskitalo, Hannu Kurki-Suonio, Vesa Muhonen +2 · 1 citation
Physics and Astronomy · #Adiabatic process #Anisotropy #Cosmic background radiation #Cosmic microwave background #Cosmic variance #Cosmological perturbation theory #Cosmology and Gravitation Theories #Curvature #Electrical and Electromagnetic Research #Galaxies: Formation, Evolution, Phenomena #Perturbation (astronomy) #Planck #astro-ph #hep-ph
paper · pdf · doi:10.1088/1475-7516/2007/09/008
published as JCAP0709:008,2007 · v1&2: 4 pages, 2 figures. v4: 16 pages, 7 figures, iopart style. Revised the 'Other cosmological data' section, added a detailed discussion on the effect of priors, and added many figures. Published version
openalex publication_date 2007/09/11 · arxiv created 2007/09/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The improved data on the cosmic microwave background (CMB) anisotropy allow a better determination of the adiabaticity of the primordial perturbation. Interestingly, we find that recent CMB data seem to favor a contribution of a primordial isocurvature mode where the entropy perturbation is positively correlated with the primordial curvature perturbation and has a large spectral index ( n iso ∼ 3). With four additional parameters we obtain a better fit to the CMB data by Δχ 2 = 9.7 compared to an adiabatic model. For this best-fit model the non-adiabatic contribution to the CMB temperature variance is 4%. According to a Markov chain Monte Carlo analysis the non-adiabatic contribution is positive at more than 95% confidence level. The exact confidence level depends somewhat on the choice of priors, and we discuss the effect of different priors as well as additional cosmological data.