We present a power spectrum analysis of the final 2dF Galaxy Redshift Survey , employing a direct Fourier method .
The sample used comprises 221 414 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 rest-frame colour , and deducing a self-consistent treatment of k -corrections and evolution for each population .
The covariance matrix for the power-spectrum 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 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 \Omega _ { m } h = 0.168 \pm 0.016 and a baryon fraction \Omega _ { b } / \Omega _ { m } = 0.185 \pm 0.046 ( 1 \sigma errors ) .
The value of \Omega _ { m } h is 1 \sigma lower than the 0.20 \pm 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 \Omega _ { m } = 0.3 : in combination with CMB data from WMAP , we infer \Omega _ { m } = 0.231 \pm 0.021 .