A. Iovino

A Homogeneous Bright Quasar Survey

In undertaking a large shallow survey for quasars, we considered especially two issues: (I) On the one hand, the shape of the Luminosity Function and the determination of the form of evolution as L ∝ (1 + z) k or L ∝ e T/τ are uncertain. Trends of this form, potentially telling about the mechanism to fuel the central engine (in principle they can reveal if the QSO phenomenon is driven by the surrounding environment or is determined by its nuclear conditions only), can be spuriously favoured by fits that overlook the observational biases. To probe the real trend, not only the database at faint magnitudes and higher redshifts has to be enlarged, but also the incompleteness at bright magnitudes should be bound or removed with better samples allowing an adequately sophisticated analysis.

The Evolution of Structure

A summary is given of recent observational work pertaining to the evolution of large scale structure, with particular reference to quasar clustering and the Lyα forest.

Void Structure in the Lyman Alpha Forest

using a model of the present structure of the Universe, it is shown that voids are less pronounced in the ditribution of Lyα absorbers at high redshift than they are in the distribution of galaxies today.

The clustering of quasars

In an attempt to obtain the highest possible sensitivity to quasar clustering using homogeneous samples, we have combined four deep surveys totalling 579 quasars. This reveals a 5.5σ excess of pairs with separations ≤ 10h −1 Mpc at z ≤ 1.5.

Clustering of Quasars from the ROE/ESO Large-Scale AQD Survey for Quasars

The new ROE/ESO large-scale AQD survey for quasars forms a connected area of ~ 200 deg2 near the south galactic pole, and has resulted in the discovery of a total number of quasar candidates that is comparable to the number previously published from all other sources (see the poster paper by Iovino, Clowes & Shaver at this conference). In this paper we describe the first results of a three-dimensional self-clustering analysis of ~ 1100 “high-probability” candidates occupying the assigned-redshift band of 1.8 to 2.4. Although the analysis is sensitive to very weak clustering we find no evidence that quasars are distributed in any way other than randomly. The implications of this result are discussed.