Large-Scale Structure from 2dFGRS

Abstract

The 2dF Galaxy Redshift Survey is now complete, and the full data are public. 2dFGRS was the first survey to observe more than 100,000 redshifts, making possible precise measurements of many aspects of galaxy clustering, which can be studied as a function of galaxy spectral type, and also of broad-band colour. Early-type galaxies are more strongly clustered than late types, with a relative bias of b = 1.25 ± 0.09 on large scales. For both types, luminosity dependence of clustering is detected at high significance, and is well described by a relative bias of b/b* = 0.85 + 0.15(L/L*). This is consistent with the observation that L* in rich clusters is brighter than the global value by 0.28 ± 0.08 mag. Redshift-space distortions from large-scale infall velocities measure the distortion parameter β = Ω0.6m/b = 0.49 ± 0.09. The power spectrum is measured to ≲ 10% accuracy for k > 0.02 h Mpc--1, and is well fitted by a CDM model with Ωmh = 0.18 ± 0.02 and a baryon fraction of 0.17 ± 0.06. The 2dFGRS plays an essential role in breaking model degeneracies inherent in CMB data; a joint analysis with WMAP results requires Ωm = 0.25 ± 15% and h = 0.73 ± 5%, assuming scalar fluctuations.