The LABOCA survey of the Extended Chandra Deep Field-South: clustering of submillimetre galaxies

We present a measurement of the spatial clustering of submillimetre galaxies (SMGs) at z = 1-3. Using data from the 870 m Large APEX Bolometer Camera (LABOCA) submillimetre survey of the Extended Chandra Deep Field-South, we employ a novel technique to measure the cross-correlation between SMGs and galaxies, accounting for the full probability distributions for photometric redshifts of the galaxies. From the observed projected two-point crosscorrelation function we derive the linear bias and characteristic dark matter halo masses for the SMGs. We detect clustering in the cross-correlation between SMGs and galaxies at the >4 level. Accounting for the clustering of galaxies from their autocorrelation function, we estimate an autocorrelation length for SMGs of r 0 = 7.7 +1.8 -2.3 h -1 Mpc assuming a power-law slope = 1.8, and derive a corresponding dark matter halo mass of log(M halo h -1 M ) = 12.8 +0.3 -0.5 . Based on the evolution of dark matter haloes derived from simulations, we show that that the z = 0 descendants of SMGs are typically massive (2-3L * ) elliptical galaxies residing in moderate-to high-mass groups (log(M halo h -1 M ) = 13.3 +0.3 -0.5 ). From the observed clustering we estimate an SMG lifetime of 100 Myr, consistent with lifetimes derived from gas consumption times and star formation time-scales, although with considerable uncertainties. The clustering of SMGs at z 2 is consistent with measurements for optically selected quasistellar objects (QSOs), supporting evolutionary scenarios in which powerful starbursts and QSOs occur in the same systems. Given that SMGs reside in haloes of characteristic mass 6 10 12 h -1 M , we demonstrate that the redshift distribution of SMGs can be described remarkably well by the combination of two effects: the cosmological growth of structure and the evolution of the molecular gas fraction in galaxies. We conclude that the powerful starbursts in SMGs likely represent a short-lived but universal phase in massive galaxy evolution, associated with the transition between cold gas-rich, star-forming galaxies and passively evolving systems.