We present the final catalogue of the 2dF QSO Redshift Survey (2QZ), based on Anglo‐Australian Telescope 2dF spectroscopic observations of 44 576 colour‐selected (ubJr) objects with 18.25 < bJ < 20.85 selected from automated plate measurement scans of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23 338 quasi‐stellar objects (QSOs), 12 292 galactic stars (including 2071 white dwarfs) and 4558 compact narrow emission‐line galaxies. We obtained a reliable spectroscopic identification for 86 per cent of objects observed with 2dF. We also report on the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1564 brighter(16 < bJ < 18.25) sources selected from the same photographic input catalogue. In total, we identified 322 QSOs spectroscopically in the 6QZ. The completed 2QZ is, by more than a factor of 50, the largest homogeneous QSO catalogue ever constructed at these faint limits (bJ < 20.85) and high QSO surface densities (35 QSOs deg−2). As such, it represents an important resource in the study of the Universe at moderate‐to‐high redshifts. As an example of the results possible with the 2QZ, we also present our most recent analysis of the optical QSO luminosity function and its cosmological evolution with redshift. For a flat, Ωm= 0.3 and ΩΛ= 0.7, universe, we find that a double power law with luminosity evolution that is exponential in look‐back time, τ, of the form L b J*(z)∝ e6.15τ, equivalent to an e‐folding time of 2 Gyr, provides an acceptable fit to the redshift dependence of the QSO LF over the range 0.4 < z < 2.1 and M b J < −22.5. Evolution described by a quadratic in redshift is also an acceptable fit, with L b J*(z)∝ 10 1.39italicz−0.29italicz 2.

In this paper we present a clustering analysis of quasi‐stellar objects (QSOs) using over 20 000 objects from the final catalogue of the 2dF QSO Redshift Survey (2QZ), measuring the redshift‐space two‐point correlation function, ξ(s). When averaged over the redshift range 0.3 < z < 2.2 we find that ξ(s) is flat on small scales, steepening on scales above ∼25 h−1 Mpc. In a WMAP/2dF cosmology (Ωm= 0.27, ΩΛ= 0.73) we find a best‐fitting power law with s0= 5.48+0.42−0.48 h−1 Mpc and γ= 1.20 ± 0.10 on scales s= 1 to 25 h−1 Mpc. We demonstrate that non‐linear redshift‐space distortions have a significant effect on the QSO ξ(s) at scales less than ∼10 h−1 Mpc. A cold dark matter model assuming WMAP/2dF cosmological parameters is a good description of the QSO ξ(s) after accounting for non‐linear clustering and redshift‐space distortions, and allowing for a linear bias at the mean redshift of bQ(z= 1.35) = 2.02 ± 0.07. We subdivide the 2QZ into 10 redshift intervals with effective redshifts from z= 0.53 to 2.48. We find a significant increase in clustering amplitude at high redshift in the WMAP/2dF cosmology. The QSO clustering amplitude increases with redshift such that the integrated correlation function, , within 20 h−1 Mpc is and . We derive the QSO bias and find it to be a strong function of redshift with bQ(z= 0.53) = 1.13 ± 0.18 and bQ(z= 2.48) = 4.24 ± 0.53. We use these bias values to derive the mean dark matter halo (DMH) mass occupied by the QSOs. At all redshifts 2QZ QSOs inhabit approximately the same mass DMHs with MDH= (3.0 ± 1.6) × 1012 h−1  M⊙, which is close to the characteristic mass in the Press–Schechter mass function, M*, at z= 0. These results imply that L*Q QSOs at z∼ 0 should be largely unbiased. If the relation between black hole (BH) mass and MDH or host velocity dispersion does not evolve, then we find that the accretion efficiency (L/LEdd) for L*Q QSOs is approximately constant with redshift. Thus the fading of the QSO population from z∼ 2 to ∼0 appears to be due to less massive BHs being active at low redshift. We apply different methods to estimate, tQ, the active lifetime of QSOs and constrain tQ to be in the range 4 × 106–6 × 108 yr at z∼ 2. We test for any luminosity dependence of QSO clustering by measuring ξ(s) as a function of apparent magnitude (equivalent to luminosity relative to L*Q). However, we find no significant evidence of luminosity‐dependent clustering from this data set.

We present a spectroscopic survey of almost 15,000 candidate intermediate-redshift Luminous Red Galaxies (LRGs) brighter than i=19.8, observed with 2dF on the Anglo-Australian Telescope. The targets were selected photometrically from the Sloan Digital Sky Survey (SDSS) and lie along two narrow equatorial strips covering 180 sq deg. Reliable redshifts were obtained for 92% of the targets and the selection is very efficient: over 90% have redshifts between 0.45 and 0.8. More than 80% of the ~11,000 red galaxies have pure absorption-line spectra consistent with a passively-evolving old stellar population. The redshift, photometric and spatial distributions of the LRGs are described. The 2SLAQ data will be released publicly from mid-2006, providing a powerful resource for observational cosmology and the study of galaxy evolution.Comment: Accepted for publication in MNRAS. 21 pages. The 2SLAQ LRG data discussed in this paper will become public when the paper appears in the journal. See http://www.2slaq.info for more information on the survey and data release, and a higher resolution version of the pape

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We have generated a series of composite quasi-stellar object (QSO) spectra using over 22 000 individual low-resolution (∼8-Å) QSO spectra obtained from the 2dF (18.25 < b J < 20.85) and 6dF (16 < b J 18.25) QSO Redshift Surveys. The large size of the catalogue has enabled us to construct composite spectra in relatively narrow redshift ( z = 0.25) and absolute magnitude ( M B = 0.5) bins. The median number of QSOs in each composite spectrum is ∼200, yielding typical signal-to-noise ratios of ∼100. For a given redshift interval, the composite spectra cover a factor of over 25 in luminosity. For a given luminosity, many of the major QSO emission lines (e.g. Mg II λ2798, [O II] λ3727) can be observed over a redshift range of 1 or greater.Using the composite spectra we have measured the line strengths (equivalent widths) of the major broad and narrow emission lines. We have also measured the equivalent width of the Ca II λ3933 K absorption feature caused by the host galaxy of the active galactic nuclei (AGN). Under the assumption of a fixed host galaxy spectral energy distribution (SED), the correlation seen between Ca II K equivalent width and source luminosity implies L gal ∝ L 0.42 ± 0.05 QSO . We find strong anticorrelations with luminosity for the equivalent widths of [O II] λ3727 and [Ne V] λ3426. These provide hints to the general fading of the NLR in high-luminosity sources, which we attribute to the NLR dimensions becoming larger than the host galaxy. This could have important implications for the search for type 2 AGN at high redshifts. If average AGN host galaxies have SEDs similar to average galaxies, then the observed narrow [O II] emission could be solely a result of the host galaxy at low luminosities (M B ∼ −20). This suggests that the [O II] line observed in high-luminosity AGN may be emitted, to a large part, by intense star-forming regions. The AGN contribution to this line could be weaker than previously assumed.We measure highly significant Baldwin effects for most broad emission lines (C IV λ1549, C III] λ1909, Mg II λ2798, Hγ , Hβ) and show that they are predominantly caused by correlations with luminosity, not redshift. We find that the Hβ and Hγ Balmer lines show an inverse Baldwin effect and are positively correlated with luminosity, unlike the broad ultraviolet lines. We postulate that this previously unknown effect is caused by a luminosity-dependent change in the ratio of disc to non-disc continuum components.The correlation of quasi-stellar object (QSO) emission-line properties with luminosity is a straightforward yet potentially highly informative test of standard physical models for active galactic C 2002 RAS