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 _ { \mbox { \tiny { vega } } } \leq 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 0.20 \pm 0.01 mJy ( 20.0 \sigma ) , 0.45 \pm 0.04 mJy ( 11.3 \sigma ) , 0.42 \pm 0.03 mJy ( 14.0 \sigma ) , and 0.41 \pm 0.04 mJy ( 10.3 \sigma ) for the K _ { \mbox { \tiny { vega } } } \leq 20 , BzK , ERO and DRG samples , respectively .
For the BzK , ERO and DRG subsamples , which overlap to some degree and are like to be at z \simeq 1 - 2 , this implies an average far-IR luminosity of \sim 2 - 6 \times 10 ^ { 11 } \mbox { $ L _ { \odot } $ } and star formation rate of \sim 40 - 100 \mbox { $ M _ { \odot } $ } .
Splitting the BzK galaxies up into star-forming ( sBzK ) and passive ( pBzK ) galaxies , the former is significantly detected ( 0.48 \pm 0.04 mJy , 12.0 \sigma ) while the latter is only marginally detected ( 0.27 \pm 0.10 mJy , 2.7 \sigma ) , thus confirming that the sBzK/pBzK criteria do isolate obscured , star forming and truly passive galaxies .
The K _ { \mbox { \tiny { vega } } } \leq 20 galaxies are found to contribute with 6.6 \pm 0.3 Jy deg ^ { -2 } ( \sim 15 \% ) to the 870- \mu m extragalactic background light ( EBL ) .
sBzK and pBzK galaxies contribute 1.7 \pm 0.2 Jy deg ^ { -2 } ( \sim 4 \% ) and 0.2 \pm 0.1 Jy deg ^ { -2 } ( < 0.5 \% ) to the EBL .
We present the first delineation of the average submm signal from K _ { \mbox { \tiny { vega } } } \leq 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 star formation rate ) by a factor \sim 2 - 3 from z \sim 2 to z \sim 0 .
This is in line with a cosmic star formation history in which the star formation activity in galaxies increases significantly at z \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle > $ } \kern - 6.0 pt \lower 1.72 pt \hbox { { $% \scriptstyle \sim$ } } } 1 .
A linear correlation between the average 24- \mu m and 870- \mu m flux densities is found for K _ { \mbox { \tiny { vega } } } \leq 20 galaxies with 24- \mu m fluxes \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle < $ } \kern - 6.0 pt \lower 1.72 pt \hbox { { $% \scriptstyle \sim$ } } } 350 \mu Jy ( corresponding to L _ { \mbox { \tiny { IR } } } \simeq 1.5 \times 10 ^ { 12 } \mbox { $ L _ { \odot } $ } a z \simeq 2 ) , while at higher 24- \mu m fluxes there is no correlation .
This behaviour suggests that star formation , and not Active Galactic Nuclei ( AGN ) , is in general responsible for the bulk of the mid-IR emission of L _ { \mbox { \tiny { IR } } } \mathrel { \raise 1.505 pt \hbox { $ \scriptstyle < $ } \kern - 6.0 pt% \lower 1.72 pt \hbox { { $ \scriptstyle \sim$ } } } 1.5 \times 10 ^ { 12 } \mbox { $ L _ { % \odot } $ } 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 vs . z - K diagram we have confirmed the ability of the sBzK-selection criterion to select starforming galaxies at z > 1 , although our analysis suggest that the subset of sBzK galaxies which are also EROs are responsible for > 80 \% of the submm emission from the entire sBzK population .