Cosmological parameters from cosmic microwave background measurements and the final 2dF Galaxy Redshift Survey power spectrum

• Published in: Monthly notices of the Royal Astronomical Society 2006-02, Vol.366 (1), p.189-207
• Main Authors: Sánchez, Ariel G., Baugh, C. M., Percival, W. J., Peacock, J. A., Padilla, N. D., Cole, S., Frenk, C. S., Norberg, P.
• Format: Article
• Language: English
• Subjects: Astronomy; cosmic microwave background; cosmological parameters; Cosmology; Density; Earth, ocean, space; Exact sciences and technology; large-scale structure of Universe; Measurement techniques; Microwave communications; Stars & galaxies
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2005.09833.x

We derive constraints on cosmological parameters using the power spectrum of galaxy clustering measured from the final 2dF Galaxy Redshift Survey (2dFGRS) and a compilation of measurements of the temperature power spectrum and temperature-polarization cross-correlation of the cosmic microwave background radiation. We analyse a range of parameter sets and priors, allowing for massive neutrinos, curvature, tensors and general dark energy models. In all cases, the combination of data sets tightens the constraints, with the most dramatic improvements found for the density of dark matter and the energy density of dark energy. If we assume a flat universe, we find a matter density parameter of Ωm= 0.237 ± 0.020, a baryon density parameter of Ωb= 0.041 ± 0.002, a Hubble constant of H0= 74 ± 2 kms−1 Mpc−1, a linear theory matter fluctuation amplitude of σ8= 0.77 ± 0.05 and a scalar spectral index of ns= 0.954 ± 0.023 (all errors show the 68 per cent interval). Our estimate of ns is only marginally consistent with the scale-invariant value ns= 1; this spectrum is formally excluded at the 95 per cent confidence level. However, the detection of a tilt in the spectrum is sensitive to the choice of parameter space. If we allow the equation of state of the dark energy to float, we find wDE=−0.85+0.18−0.17, consistent with a cosmological constant. We also place new limits on the mass fraction of massive neutrinos: ƒν < 0.105 at the 95 per cent level, corresponding to ∑mν < 1.2 eV.