Tracing high redshift cosmic web with quasar systems. Invited talk at IAU Symposium 308

TL;DR

This study uses quasar data from SDSS DR7 to map the cosmic web at high redshifts 1.0 to 1.8, revealing structures comparable to local superclusters and differences from random distributions, aiding understanding of large-scale cosmic structure.

Contribution

It introduces a method to identify and analyze quasar systems at high redshift, providing new insights into the cosmic web's structure and its comparison to local universe superclusters.

Findings

Quasar systems at small linking lengths are smaller than random systems.

Mean space density of quasar systems matches local supercluster densities.

Large quasar systems exceed 500 Mpc/h in diameter.

Abstract

We study the cosmic web at redshifts 1.0 <= z <= 1.8 using quasar systems based on quasar data from the SDSS DR7 QSO catalogue. Quasar systems were determined with a friend-of-friend (FoF) algorithm at a series of linking lengths. At the linking lengths l <= 30 Mpc/h the diameters of quasar systems are smaller than the diameters of random systems, and are comparable to the sizes of galaxy superclusters in the local Universe. The mean space density of quasar systems is close to the mean space density of local rich superclusters. At larger linking lengths the diameters of quasar systems are comparable with the sizes of supercluster complexes in our cosmic neighbourhood. The richest quasar systems have diameters exceeding 500 Mpc/h. Very rich systems can be found also in random distribution but the percolating system which penetrate the whole sample volume appears in quasar sample at smaller linking length than in random samples showing that the large-scale distribution of quasar systems differs from random distribution. Quasar system catalogues at our web pages (http://www.aai.ee/~maret/QSOsystems.html) serve as a database to search for superclusters of galaxies and to trace the cosmic web at high redshifts.