Correlated Mixture Between Adiabatic and Isocurvature Fluctuations and Recent CMB Observations

Details Correlated Mixture Between Adiabatic and Isocurvature Fluctuations and Recent CMB Observations Correlated Mixture Between Adiabatic and Isocurvature Fluctuations and Recent CMB Observations

2005-01-18

arxiv.org/abs/astro-ph/0501399v1

Phys.Rev. D71 (2005) 043501

Astronomy and Astrophysics

Astrophysics

Accepted for publication in Physical Review D

Scientific paper

10.1103/PhysRevD.71.043501

This work presents a reduced chi^2_nu test to search for non-gaussian signals in the CMBR TT power spectrum of recent CMBR data, WMAP, ACBAR and CBI data sets, assuming a mixed density field including adiabatic and isocurvature fluctuations. We assume a skew positive mixed model with adiabatic inflation perturbations plus additional isocurvature perturbations possibly produced by topological defects. The joint probability distribution used in this context is a weighted combination of Gaussian and non-Gaussian random fields. Results from simulations of CMBR temperature for the mixed field show a distinct signature in CMB power spectrum for very small deviations (~ 0.1%) from a pure Gaussian field, and can be used as a direct test for the nature of primordial fluctuations. A reduced chi^2_nu test applied on the most recent CMBR observations reveals that an isocurvature fluctuations field is not ruled out and indeed permits a very good description for a flat geometry Lambda-CDM universe, chi^2_930 ~ 1.5, rather than the simple inflationary standard model with chi^2_930 ~ 2.3. This result may looks is particular discrepant with the reduced chi^2 of 1.07 obtained with the same model in Spergel et al. (2003) for temperature only, however, our work is restricted to a region of the parameter space that does not include the best fit model for TT only of Spergel et al. (2003).

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