Detection of Large Scale Structures at z~0.8 and z~1.2

Preprint
Publisher Website
Google Scholar
  • 23 January 2003
Abstract
We report the finding of two large-scale structures in a wide-field (40'x35') optical (V- and I-band) imaging survey of a field towards two known concentrations of quasars and MgII absorbers at z~0.8 and z~1.2. We are able to select high-redshift (0.6<z<1.3) early-type galaxies as those redder than the cluster red sequence at z=0.5 and having I<23.5. Through comparison with a 35'x35' control field, we find a 30% excess of these red galaxies corresponding to 563 galaxies across the field. The colour distribution of the excess shows a coherent peak at 2.7<V-I<3.1, and the magnitude distribution is well described by a Schechter function. Together they show unambiguously that the galaxy excess is primarily due to a population of early-type galaxies at z=0.83\pm0.08. In follow-up NIR imaging of the four best cluster candidates in the field we identify three clusters at z~0.8 each having clear red sequences of ~20 galaxies at I-K=3.4, forming a structure 20 Mpc across. A previously identified cluster at z~1.2 is confirmed with 28 galaxies having VIJK colours consistent with passively-evolving galaxies at z~1.2 within 1 arcmin of the cluster centre. In all four fields red sequences are apparent at both I-K=3.4 and I-K=4.1 indicating large-scale structures at z~0.8 and z~1.2 extending across the whole optical field (20-30 Mpc). The full extents of the two large-scale structures are believed to be much greater, both being traced by superstructures of quasars and MgII absorbers, including the Clowes-Campusano Large Quasar Group (LQG) of 23 quasars at z~1.2, the largest known structure in the early Universe having a maximal extent of ~200 Mpc. In both cases, there is evidence directly connecting the large-scale structures of galaxies found here and the quasar / MgII superstructures that trace them.

This publication has 0 references indexed in Scilit: