Superclustering of Galaxies Traced by a Group of QSOS at Z = 1.1

Abstract

We present the result of a wide-area (48′ x 9′) imaging  survey of faint galaxies toward the 1338+27 field where an unusual concentration of five QSOs at z ~ 1.1 is known to exist. We have detected a significant clustering signature of faint red galaxies with I > 21 and R — I > 1.2 over a scale extending to ~ 20h ⁻¹₅₀ Mpc at z ~ 1.1. The R — I colors of these galaxies and the angular correlation function analysis strongly suggests that these galaxies are indeed at the redshift of the group of five QSOs. Our new K′-band images for three selected density peaks also supported the idea. Since this group of five QSOs are indeed a part of much larger (~ 70h ⁻¹₅₀ Mpc) clustering of 23 QSOs discovered by Crampton et al. (1988), the whole size of the detected structure may be as large as the local “Great Wall” structure.