Constraints on isocurvature models from the WMAP first-year data

Journal Article · Mon Nov 15 04:00:00 EST 2004 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.70.103520· OSTI ID:20697991

Moodley, K ^[1]; Bucher, M ^[2]; Dunkley, J; Ferreira, P G; Skordis, C ^[3]

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1. Astrophysics and Cosmology Research Unit and School of Mathematical Sciences, University of KwaZulu-Natal, Durban, 4041 (South Africa)
2. Laboratoire de Physique theorique, Universite Paris-Sud, 91405 Orsay (France)
3. Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

We investigate the constraints imposed by the first-year Wilkinson Microwave Anisotropy Probe (WMAP) cosmic microwave background (CMB) data extended to higher multipoles by data from ACBAR, BOOMERANG, CBI, and the VSA and by the large-scale structure data from the 2dF galaxy redshift survey on the possible amplitude of primordial isocurvature modes. A flat universe with cold dark matter (CDM) and cosmological constant {lambda} is assumed, and the baryon, CDM isocurvature (CI), and neutrino density (NID), and velocity (NIV) isocurvature modes are considered. Constraints on the allowed isocurvature contributions are established from the data for various combinations of the adiabatic mode and one, two, and three isocurvature modes, with intermode cross correlations allowed. Since baryon and CDM isocurvature are observationally virtually indistinguishable, these modes are not considered separately. We find that when just a single isocurvature mode is added, the present data allows an isocurvature fraction, in terms of the nonadiabatic contribution to the power in the CMB anisotropy, as large as 13{+-}6, 7{+-}4, and 13{+-}7 percent for adiabatic plus the CI, NID, and NIV modes, respectively. When two isocurvature modes plus the adiabatic mode and cross correlations are allowed, these percentages rise to 47{+-}16, 34{+-}12, and 44{+-}12 for the combinations CI+NID, CI+NIV, and NID+NIV, respectively. Finally, when all three isocurvature modes and cross correlations are allowed, the admissible isocurvature fraction rises to 57{+-}9 percent. In our analysis we consider only scalar modes with a single common tilt parameter for all the modes and do not consider any possible primordial anisotropies in the local neutrino velocity distribution beyond quadrupole order. The sensitivity of the results to the choice of prior probability distribution is examined.

• OSTI ID: 20697991
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 10 Vol. 70; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
ANISOTROPY
BARYONS
CORRELATIONS
COSMIC RADIATION
COSMOLOGICAL CONSTANT
COSMOLOGY
DENSITY
DISTRIBUTION
GALAXIES
GALAXY CLUSTERS
NEUTRINOS
NONLUMINOUS MATTER
PROBABILITY
QUADRUPOLES
RADIOWAVE RADIATION
RED SHIFT
RELICT RADIATION
SCALARS
UNIVERSE