Clustering of submillimeter-selected galaxies

Using accurate positions from very deep radio observations to guide multiobject Keck spectroscopy, we have determined a substantially complete redshift distribution for very luminous distant submillimeter-selected galaxies (SMGs). A sample of 73 redshifts for SMGs in seven fields contains a surprisingly large number of associations'': systems of SMGs with Mpc-scale separations and redshifts within 1200 km s(-1). This sample provides tentative evidence of strong clustering of SMGs at z similar or equal to 2-3 with a correlation length of similar to(6.9 +/- 2.1) h(-1) Mpc, using a simple pair-counting approach that is appropriate to the small, sparse SMG samples. This is somewhat greater than the well-determined correlation lengths for both z similar or equal to 3 optical-UV color-selected Lyman break galaxies (LBGs) and z similar or equal to 2 QSOs. This could indicate that SMGs trace the densest large-scale structures in the high-redshift universe and that they may either be evolutionarily distinct from LBGs and QSOs or subject to a more complex astrophysical bias.