The 2dF Galaxy Redshift Survey: powerspectrum analysis of the final data set and cosmological implications
Abstract
We present a powerspectrum analysis of the final 2dF Galaxy Redshift Survey (2dFGRS), employing a direct Fourier method. The sample used comprises 221414 galaxies with measured redshifts. We investigate in detail the modelling of the sample selection, improving on previous treatments in a number of respects. A new angular mask is derived, based on revisions to the photometric calibration. The redshift selection function is determined by dividing the survey according to restframe colour, and deducing a selfconsistent treatment of kcorrections and evolution for each population. The covariance matrix for the powerspectrum estimates is determined using two different approaches to the construction of mock surveys, which are used to demonstrate that the input cosmological model can be correctly recovered. We discuss in detail the possible differences between the galaxy and mass power spectra, and treat these using simulations, analytic models and a hybrid empirical approach. Based on these investigations, we are confident that the 2dFGRS power spectrum can be used to infer the matter content of the universe. On large scales, our estimated power spectrum shows evidence for the `baryon oscillations' that are predicted in cold dark matter (CDM) models. Fitting to a CDM model, assuming a primordial n_{s}= 1 spectrum, h= 0.72 and negligible neutrino mass, the preferred parameters are Ω_{m}h= 0.168 +/ 0.016 and a baryon fraction Ω_{b}/Ω_{m}= 0.185 +/ 0.046 (1σ errors). The value of Ω_{m}h is 1σ lower than the 0.20 +/ 0.03 in our 2001 analysis of the partially complete 2dFGRS. This shift is largely due to the signal from the newly sampled regions of space, rather than the refinements in the treatment of observational selection. This analysis therefore implies a density significantly below the standard Ω_{m}= 0.3: in combination with cosmic microwave background (CMB) data from the Wilkinson Microwave Anisotropy Probe (WMAP), we infer Ω_{m}= 0.231 +/ 0.021.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 2005
 DOI:
 10.1111/j.13652966.2005.09318.x
 arXiv:
 arXiv:astroph/0501174
 Bibcode:
 2005MNRAS.362..505C
 Keywords:

 cosmological parameters;
 largescale structure of Universe;
 Astrophysics
 EPrint:
 Updated to match the in press MNRAS version. P(k) data and covariance matrix available at http://www.mso.anu.edu.au/2dFGRS/Public/Release/PowSpec