The 2dF Galaxy Redshift Survey: the power spectrum and the matter content of the Universe

The 2dF Galaxy Redshift Survey has now measured in excess of 160 000 galaxy redshifts. This paper presents the power spectrum of the galaxy distributi on, calculated using a direct Fourier transform based technique. We argue t hat, within the k-space region 0.02 less than or similar to k less than or similar to 0.15 h Mpc(-1), the shape of this spectrum should be close to th at of the linear density perturbations convolved with the window function o f the survey. This window function and its convolving effect on the power s pectrum estimate are analysed in detail. By convolving model spectra, we ar e able to fit the power-spectrum data and provide a measure of the matter c ontent of the Universe. Our results show that models containing baryon osci llations are mildly preferred over featureless power spectra. Analysis of t he data yields 68 per cent confidence limits on the total matter density ti mes the Hubble parameter Omega (m) h = 0.20 +/- 0.03, and the baryon fracti on Omega (b)/Omega (m) = 0.15 +/- 0.07, assuming scale-invariant primordial fluctuations.