Primordial Isocurvature Perturbations: Testing the Adiabaticity of the CMB Anisotropy

Abstract

Prospects for testing the adiabaticity of the primordial cosmological perturbations using MAP and PLANCK are evaluated. The most general cosmological perturbation in a universe with just baryons, photons, neutrinos, and a cold dark matter (CDM) component is described. In addition to the familiar adiabatic mode, there are four nonsingular isocurvature modes: a baryon isocurvature mode, a CDM isocurvature mode, a neutrino density isocurvature mode, and a neutrino velocity isocurvature mode. The most general perturbation is described by a 5x5, positive-definite, symmetric, matrix-valued function of wave number whose off-diagonal elements represent the correlations between the above mentioned modes. We found that when three modes and their correlations are admitted, the fractional uncertainties in the cosmological parameters and amplitudes of the isocurvature modes and their correlations become of order unity. These degeneracies, however, can be broken with the polarization information provided by PLANCK, reducing the uncertainties to below the ten percent level. Polarization is thus crucial to testing the adiabaticity of the primordial fluctuations.

7 pages revtex, one postscript figure. To appear in the proceedings of the CAPP2000 Conference, Verbier Switzerland, July 2000

References in corpus (5)

• CMB Observables and Their Cosmological Implications
• Correlated adiabatic and isocurvature perturbations from double inflation
• The General Primordial Cosmic Perturbation
• Limits on isocurvature fluctuations from Boomerang and MAXIMA
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• The cosmic microwave background bispectrum from the non-linear evolution of the cosmological perturbations
• Isocurvature modes and Baryon Acoustic Oscillations
• Isocurvature modes and Baryon Acoustic Oscillations II: gains from combining CMB and Large Scale Structure
• Probing Compensated Isocurvature with the 21-cm Signal during Cosmic Dawn
• Initial conditions of the universe: A sign of the sine mode
• Origin & evolution of the Universe