Towards a refined cosmic concordance model: Joint 11-parameter constraints from the cosmic microwave background and large-scale structure

Max Tegmark, Matias Zaldarriaga, and Andrew J. S. Hamilton
Phys. Rev. D 63, 043007 – Published 30 January 2001
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Abstract

We present a method for calculating large numbers of power spectra Cl and P(k) that accelerates CMBFAST by a factor around 103 without appreciable loss of accuracy, then apply it to constrain 11 cosmological parameters from current cosmic microwave background (CMB) and large scale structure (LSS) data. While the CMB alone still suffers from several degeneracies, allowing, e.g., closed models with strong tilt and tensor contributions, the shape of the real space power spectrum of galaxies from the IRAS Point Source Catalogue Redshift (PSCz) survey breaks these degeneracies and helps place strong constraints on most parameters. At 95% confidence, the combined CMB and LSS data imply a baryon density 0.020<ωb<0.037, dark matter density 0.10<ωdm<0.32 with a neutrino fraction fν<38%, vacuum density ΩΛ<0.76, curvature 0.19<Ωk<0.10, scalar tilt 0.86<ns<1.16, and reionization optical depth τ<0.44. These joint constraints are quite robust, changing little when we impose priors on the Hubble parameter, tilt, flatness, gravity waves or reionization. Adding nucleosynthesis and neutrino priors on the other hand tightens constraints considerably, requiring ΩΛ>0.49 and a red-tilt, ns<1. The analysis allows a number of consistency tests to be made, all of which pass. At the 95% level, the flat scalar “concordance model” with ΩΛ=0.62,ωdm=0.13,ωb=0.02,fν0,ns=0.9,τ=0.1,h=0.63 is consistent with the CMB and LSS data considered here, with big bang nucleosynthesis, cluster baryon fractions and cluster abundance. The inferred PSCz bias b1.2 agrees with the value estimated independently from redshift space distortions. The inferred cosmological constant value agrees with the one derived independently from SNIa studies. Cosmology seems to be on the right track.

  • Received 15 August 2000

DOI:https://doi.org/10.1103/PhysRevD.63.043007

©2001 American Physical Society

Authors & Affiliations

Max Tegmark*

  • Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104

Matias Zaldarriaga

  • Institute for Advanced Study, Princeton, New Jersey 08540

Andrew J. S. Hamilton

  • JILA and Department of Astrophysical and Planetary Sciences, Box 440, University of Colorado, Boulder, Colorado 80309

  • *Email address: max@physics.upenn.edu
  • Email address: matiasz@ias.edu
  • Email address: Andrew.Hamilton@colorado.edu

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Vol. 63, Iss. 4 — 15 February 2001

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