Companions of Qsos at Redshift 1.1

Abstract

We discuss broad- and narrow-band imaging of 7 arcmin fields of 14 QSOs with redshift ~1.1. The narrow-band filters were chosen to detect redshifted [O II] 3727A, and the broad bands are R and I, which correspond to rest wavelengths {}~3300A and ~3800A. In 100 arcsec subfields surrounding the QSOs, we detect an excess of typically 15 detected objects over the background of 25. Several of the QSO subfields also contain an excess of blue (R-I < 1.0) galaxies compared with the other subfields. Finally, several of the QSO subfields contain an excess of galaxies with significant narrow-band flux compared with the other subfields, and many of these are also blue. Most of the QSOs are radio-quiet in a region of sky overpopulated with z=1.1 QSOs, and 3 others are radio-loud from other parts of the sky. We suggest that most of these z=1.1 QSOs are in compact groups of starbursting galaxies. In our data, there is no significant difference between radio-loud and radio-quiet QSOs. We discuss cosmic evolutionary implications.