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I. K. Söchting, R. G. Clowes (Univ. of Central Lancashire), L. E. Campusano (Universidad de Chile)
We are looking at quasar environment in the context of large-scale structure (LSS) --- a new approach, giving a more informed interpretation of quasar-galaxy correlations. We investigate how quasars trace the LSS in the form of galaxy clusters and study the relative positions and morphologies of clusters associated with quasars. Our cluster detection method is based on Voronoi tessellation applied in colour slices taking advantage of the Cluster Red Sequence. The minimal spanning tree (MST) has been used to delineate the LSS. Here, we present the results for low redshift quasars (z ~0.3) on the scale of superclusters (~60h-1 Mpc). We find that quasars follow the LSS traced by galaxy clusters. A statistical test rejects the null hypothesis that the quasars are distributed independently of the LSS in clusters at a level of significance of 0.009. None of the quasars in our radio-quite sample is located in the central area of a galaxy cluster. Some quasars, found in a very rich environment, are actually located between two very close galaxy clusters, consistent with results on z ~1 quasars suggesting that cluster mergers may be involved in one of the quasar formation mechanisms. The majority of the quasars in our sample are found in poor environments; they reside on the distant (3 - 5h-1 Mpc) peripheries of galaxy clusters.
For the full account of our analysis and discussion of the results see Söchting, Clowes, & Campusano (2001, MNRAS, submitted)
The author(s) of this abstract have provided an email address for comments about the abstract: imachura@uclan.ac.uk