X-ray QSO evolution from a very deep ROSAT survey
Monthly Notices of the Royal Astronomical Society 285:3 (1997) 547-560
Abstract:
In the deepest optically identified X-ray survey yet performed, we have identified 32 X-ray-selected QSOs to a flux limit of 2 × 10-15 erg cm-2 s-1 (0.5-2 keV). The survey, performed with the ROSAT Position Sensitive Proportional Counter (PSPC), has 89 per cent spectroscopic completeness. The QSO log(N)-log(S) relation is found to have a break to a flat slope at faint fluxes. The surface density of QSOs at the survey limit is 230 ± 40 per square degree, the largest so far of any QSO survey. We use this survey to measure the QSO X-ray luminosity function at low luminosities (LX<1044.5 erg s-1) and high redshifts (2The richness dependence of galaxy cluster correlations: results from a redshift survey of rich APM clusters
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 291:2 (1997) 305-313
Higher order statistics from the APM galaxy survey
Astrophysical Journal 444:2 (1995) 520-531
Abstract:
We apply a new statistics, the factorial moment correlators, to density maps obtained from the APM survey The resulting correlators are all proportional to the two-point correlation function, substantially amplified with an amplification nearly exponential with the total rank of the correlators. This confirms the validity of the hierarchical clustering assumption on the dynamic range examined, corresponding to 0.5-50 h-1 Mpc in three-dimensional space. The Kirkwood superposition with loop terms is strongly rejected. The structure coefficients of the hierarchy are also fitted. The high quality of the APM catalog enabled us to disentangle the various contributions from the power spectrum, small-scale nonlinear clustering, and combinatorial effects, all of which affect the amplification of the correlators. These effects should appear in correlations of clusters in a similar fashion.Erratum - the APM Galaxy Survey - Part Four - Redshifts of Rich Clusters of Galaxies
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 273:2 (1995) 528-528