A LABOCA SURVEY OF THE EXTENDED CHANDRA DEEP FIELD SOUTH-SUBMILLIMETER PROPERTIES OF NEAR-INFRARED SELECTED GALAXIES

Using the 330 hr ESO-MPG 870 mu m survey of the Extended Chandra Deep Field South (ECDF-S) obtained with the Large Apex BOlometer CAmera (LABOCA) on the Atacama Pathfinder EXperiment (APEX), we have carried out a stacking analysis at submillimeter (submm) wavelengths of a sample of 8266 near-infra-red (near-IR) selected (K-vega <= 20) galaxies, including 893 BzK galaxies, 1253 extremely red objects (EROs), and 737 distant red galaxies (DRGs), selected from the Multi-wavelength Survey by Yale-Chile (MUSYC). We measure average 870 mu m fluxes of 0.22 +/- 0.01 mJy (22.0 sigma), 0.48 +/- 0.04 mJy (12.0 sigma), 0.39 +/- 0.03 mJy (13.0 sigma), and 0.43 +/- 0.04 mJy (10.8 sigma) for the K-vega <= 20, BzK, ERO, and DRG samples, respectively. For the BzK, ERO, and DRG sub-samples, which overlap to some degree and are likely to be at z similar or equal to 1-2, this implies an average far-IR luminosity of similar to(1-5) x 10(11) L-circle dot and star formation rate (SFR) of similar to 20-90M(circle dot). Splitting the BzK galaxies into star-forming (sBzK) and passive (pBzK) galaxies, the former is significantly detected (0.50 +/- 0.04 mJy, 12.5 sigma) while the latter is only marginally detected (0.34 +/- 0.10 mJy, 3.4 sigma), thus confirming that the sBzK and pBzK criteria to some extent select obscured, star-forming, and truly passive galaxies, respectively. The K-vega <= 20 galaxies are found to contribute 7.27 +/- 0.34 Jy deg(-2) (16.5% +/- 5.7%) to the 870 mu m extragalactic background light (EBL). sBzK and pBzK galaxies contribute 1.49 +/- 0.22 Jy deg-2 (3.4% +/- 1.3%) and 0.20 +/- 0.14 Jy deg(-2) (0.5% +/- 0.3%) to the EBL. We present the first delineation of the average submm signal from the K-vega <= 20 selected galaxies and their contribution to the submm EBL as a function of (photometric) redshift, and find a decline in the average submm signal (and therefore IR luminosity and SFR) by a factor similar to 2-3 from z similar to 2 to z similar to 0. This is in line with a cosmic star formation history in which the star formation activity in galaxies increases significantly at z similar to 1. A linear correlation between the average 24 mu m and 870 mu m flux densities is found for the Kvega <= 20 galaxies with 24 mu m fluxes less than or similar to 350 mu Jy (corresponding to LIR similar or equal to 1.5 x 10(12) L-circle dot at z similar to 2), while at higher 24 mu m fluxes there is no correlation. This behavior suggests that star formation, and not active galactic nuclei (AGNs), is in general responsible for the bulk of the mid-IR emission of LIR similar to 1.5 x 10(12) L-circle dot systems, while in more luminous systems the AGN makes a significant contribution to the 24 mu m emission. By mapping the stacked 870 mu m signal across the B - z versus z - K diagram we have confirmed the ability of the sBzK selection criterion to select star-forming galaxies at z > 1, although our analysis suggests that the subset of sBzK galaxies which are also EROs are responsible for >80% of the submm emission from the entire sBzK population.