Studying large - scale structure with the 2 dF Galaxy Redshift Survey

The 2dF Galaxy Redshift Survey is the first to observe more than 100,000 redshifts. This allows precise measurements of many of the key statistics of galaxy clustering, in particular redshift-space distortions and the large-scale power spectrum. This paper presents the current 2dFGRS results in these areas. Redshift-space distortions are detected with a high degree of significance, confirming the detailed Kaiser distortion from large-scale infall velocities, and measuring the distortion parameter β ≡ Ω0.6 m /b = 0.43 ± 0.07. The power spectrum is measured to <∼ 10% accuracy for k > 0.02hMpc−1, and is well fitted by a CDM model with Ωmh = 0.20± 0.03 and a baryon fraction of 0.15± 0.07. A joint analysis with CMB data requires Ωm = 0.29± 0.05, assuming scalar fluctuations, but no priors on other parameters. Two methods are used to determine the large-scale bias parameter: an internal bispectrum analysis yields b = 1.04±0.11, in very good agreement with the b = 1.10±0.08 obtained from a joint 2dFGRS+CMB analysis, again assuming scalar fluctuations. These figures refer to galaxies of approximate luminosity 2L∗; luminosity dependence of clustering is detected at high significance, and is well described by b/b∗ = 0.85 + 0.15(L/L∗). 1. Aims and design of the 2dFGRS The large-scale structure in the galaxy distribution is widely seen as one of the most important relics from an early stage of evolution of the universe. The 2dF Galaxy Redshift Survey (2dFGRS) was designed to build on previous studies of this structure, with the following main aims: (1) To measure the galaxy power spectrum P (k) on scales up to a few hundred Mpc, bridging the gap between the scales of nonlinear structure and measurements from the the cosmic microwave background (CMB). ∗On behalf of the 2dF Galaxy Redshift Survey team: Matthew Colless (ANU), Ivan Baldry (JHU), Carlton Baugh (Durham), Joss Bland-Hawthorn (AAO), Terry Bridges (AAO), Russell Cannon (AAO), Shaun Cole (Durham), Chris Collins (LJMU), Warrick Couch (UNSW), Gavin Dalton (Oxford), Roberto De Propris (UNSW), Simon Driver (St Andrews), George Efstathiou (IoA), Richard Ellis (Caltech), Carlos Frenk (Durham), Karl Glazebrook (JHU), Carole Jackson (ANU), Ofer Lahav (IoA), Ian Lewis (AAO), Stuart Lumsden (Leeds), Steve Maddox (Nottingham), Darren Madgwick (IoA), Peder Norberg (Durham), Will Percival (ROE), Bruce Peterson (ANU), Will Sutherland (ROE), Keith Taylor (Caltech).