  The 2dF Galaxy Redshift Survey has now measured in excess of 160000 galaxy
redshifts. This paper presents the power spectrum of the galaxy distribution,
calculated using a direct FFT-based technique. We argue that, within the
k-space region 0.02<k<0.15 h Mpc^-1, the shape of this spectrum should be close
to that of the linear density perturbations convolved with the window function
of the survey. This window function and its convolving effect on the power
spectrum estimate are analyzed in detail. By convolving model spectra, we are
able to fit the power-spectrum data and provide a measure of the matter content
of the universe. Our results show that models containing baryon oscillations
are mildly preferred over featureless power spectra. Analysis of the data
yields 68% confidence limits on the total matter density times the Hubble
parameter \Omega_m h = 0.20 +/- 0.03, and the baryon fraction \Omega_b/\Omega_m
= 0.15 +/- 0.07, assuming scale-invariant primordial fluctuations.
