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Session 13 - Large Scale Structure & Cosmology.
Display session, Monday, January 13
Metropolitan Ballroom,
We report the first results from a new-generation survey for quasars using the 2^\circ-field, 128-fibre, multi-object spectrograph on the 2.5-m du Pont telescope at Las Campanas Observatory in Chile. Survey candidates are all objects with (U-B)<-0.3 and B\leq19.7 on digitized UK Schmidt plates. The survey will cover 140 deg^2 and produce a homogeneous, magnitude-limited catalogue of \sim1500 quasars with redshifts 0.4\leq z\leq2.2. We have so far surveyed 18.7 deg^2 and identified 183 quasars, including all 43 previously-published quasars within the selection criteria.
The survey will be used to study in detail the large (\sim200\,h^-1Mpc) quasar group discovered at z\simeq1.3 by Clowes amp; Campusano (1991, MNRAS, 249, 218) -- the largest known structure in the early Universe -- and to study the clustering of quasars in general. The group was found with sparse sampling of quasar candidates across 25 deg^2; it strikes the boundaries of this area. Our spectroscopic survey will include all\/ candidates in an area around the group of 100 deg^2, plus a 40 deg^2 control area \sim34^\circ away. This survey should allow the determination of the full extent, membership and statistical significance of the group, using the MST method of Graham, Clowes and Campusano (1995, MNRAS, 275, 790). Preliminary analysis of our new data shows that the group persists with increased membership. The measurement of the density contrast of the quasar group will be compared with theoretical expectations, and so determine the consistency of the group with formation from Gaussian density fluctuations. We will search for sub-clustering in the group and test the hypothesis that all small-scale (\le10\,h^-1Mpc) quasar clustering is attributable to large groups. Our sample will allow further investigation of the clustering of quasars in general. We will also identify and characterise any other large quasar groups in the survey using the MST method.
