The SCUBA-2 Cosmology Legacy Survey : the clustering of submillimetre galaxies in the UKIDSS UDS field

Abstract

Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in the Universe, but their true nature remains unclear; are SMGs the progenitors of the massive elliptical galaxies we see in the local Universe, or are they just a short-lived phase among more typical star-forming galaxies? To explore this problem further, we investigate the clustering of SMGs identified in the SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre (850μm) source identifications derived using a combination of radio counterparts and colour/IR selection to analyse a sample of 914 SMGs in the UKIDSS UltraDeep Survey (UDS), making this the largest high redshift sample of these galaxies to date. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of SMGs and compare them with passive and star-forming galaxies selected in the same field. We find that SMGs, on average, occupy high-mass dark matter halos(Mhalo >1013 M☉) at redshifts z > 2.5, consistent with being the progenitors of massive quiescent galaxies in present-day galaxy clusters. We also find evidence of downsizing, in which SMG activity shifts to lower mass halos at lower redshifts. Interms of their clustering and halo masses, SMGs appear to be consistent with other star-forming galaxies at a given redshift.