Clustering of Submillimetre-Selected Galaxies

Abstract

Using accurate positions from very deep radio observations to guide multi-object Keck spectroscopy, we have determined a substantially complete redshift distribution for very luminous, distant submillimetre(submm)-selected galaxies (SMGs). A sample of 75 redshifts for SMGs in 7 fields contains a surprisingly large number of ‘associations’: galaxies with redshifts within 1200 km s^–1. This small sample provides tentative evidence of strong clustering at z ≃ 2–3 with a correlation length of 7.8 ± 2.6 h₁₀₀^–1 Mpc, using a simple pair-counting approach that is appropriate to the small, sparse SMG samples. The large correlation length could either indicate that SMGs trace the densest large-scale structures in the high-redshift Universe, and are evolutionarily distinct from optical-color-selected z ≃ 3 Lyman-break galaxies (LBGs) and QSOs, or that they are subject to a complex bias.