AN ALMA SURVEY OF SUB-MILLIMETER GALAXIES IN THE EXTENDEDCHANDRADEEP FIELD SOUTH: SUB-MILLIMETER PROPERTIES OF COLOR-SELECTED GALAXIES

Abstract

We study the sub-mm properties of color-selected galaxies via a stacking analysis applied for the first time to interferometric data at sub-mm wavelengths. We base our study on 344 GHz ALMA continuum observations of ∼ 20 ′′ -wide fields centered on 86 sub-mm sources detected in the LABOCA Extended Chandra Deep Field South Sub-mm Survey (LESS). We select various classes of galaxies (K-selected, star-forming sBzK galaxies, extremely red objects and distant red galaxies) according to their optical/NIR fluxes. We find clear, > 10-σ detections in the stacked images of all these galaxy classes. We include in our stacking analysis Herschel/SPIRE data to constrain the dust SED of these galaxies. We find that their dust emission is well described by a modified black body with T dust ≈ 30 K and β = 1.6 and IR luminosities of (5 − 11) × 10 11 L ⊙ , or implied star formation rates of 75-140 M ⊙ yr −1 . We compare our results with those of previous studies based on single-dish observations at 870 µm and find that our flux densities are a factor 2-3 higher than previous estimates. The discrepancy is observed also after removing sources individually detected in ALESS maps. We report a similar discrepancy by repeating our analysis on 1.4 GHz observations of the whole ECDFS. Hence we find tentative evidence that galaxies that are associated in projected and redshift space with submm bright sources are brighter than the average population. Finally, we put our findings in the context of the cosmic star formation rate density as a function of redshift.

Estimating sizes of faint, distant galaxies in the submillimetre regime

“…In this paper, we extend the analysis of Decarli et al (2014) using the same sample selection. The selection is based on the photometric catalogue of the ECDFS assembled using the same procedure as Simpson et al (2014), using primarily data from the Wide MUltiwavelength Survey by Yale-Chile (MUSYC; Taylor et al 2009).…”

“…This sample was referred to the K Vega < 20 sample in Decarli et al (2014) and will be referred to as the K20 sample in this paper.…”

“…Daddi et al (2010b) found sizes up to 1.5 arcsec for sample of z ∼ 2 galaxies. Decarli et al (2014) used stacking to measure the submm flux density of star-forming galaxies in the Extended Chandra Deep Field South (ECDFS) with data from the ALMA. In this paper, we will build on the work by Decarli et al (2014), using the same data, but extending the analysis to focus on the sizes of the stacked sources.…”

“…Decarli et al (2014) used stacking to measure the submm flux density of star-forming galaxies in the Extended Chandra Deep Field South (ECDFS) with data from the ALMA. In this paper, we will build on the work by Decarli et al (2014), using the same data, but extending the analysis to focus on the sizes of the stacked sources. Decarli et al (2014) performed stacking on the imaged pointings, analogous to how stacking is done at other wavelengths.…”

“…In this paper, we will build on the work by Decarli et al (2014), using the same data, but extending the analysis to focus on the sizes of the stacked sources. Decarli et al (2014) performed stacking on the imaged pointings, analogous to how stacking is done at other wavelengths. However, as seen in Lindroos et al (2015), this may not be ideal for interferometric data.…”