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Title: An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies

Abstract

We study the sub-millimeter properties of color-selected galaxies via a stacking analysis applied for the first time to interferometric data at sub-millimeter wavelengths. We base our study on 344 GHz ALMA continuum observations of ∼20''-wide fields centered on 86 sub-millimeter sources detected in the LABOCA Extended Chandra Deep Field South (ECDFS) Sub-millimeter Survey. We select various classes of galaxies (K-selected, star-forming sBzK galaxies, extremely red objects, and distant red galaxies) according to their optical/near-infrared fluxes. We find clear, >10σ detections in the stacked images of all these galaxy classes. We include in our stacking analysis Herschel/SPIRE data to constrain the dust spectral energy distribution of these galaxies. We find that their dust emission is well described by a modified blackbody with T {sub dust} ≈ 30 K and β = 1.6 and infrared luminosities of (5-11) × 10{sup 11} L {sub ☉} or implied star formation rates of 75-140 M {sub ☉} yr{sup –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 amore » 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 sub-mm 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.« less

Authors:
; ; ; ;  [1]; ; ; ;  [2];  [3];  [4];  [5];  [6];  [7];  [8]; ;  [9];  [10];  [11]
  1. Max-Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  2. Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom)
  3. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  4. Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
  5. IRAM, 300 rue de la piscine, F-38406 Saint-Martin d'Hères (France)
  6. Universität Wien, Institut für Astrophysik, Türenschanzstrasse 17, A-1180 Wien (Austria)
  7. University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT (United Kingdom)
  8. Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
  9. Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala SE-439 92 (Sweden)
  10. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  11. Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
Publication Date:
OSTI Identifier:
22348269
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COLOR; COMPARATIVE EVALUATIONS; DENSITY; DETECTION; DUSTS; EMISSION; ENERGY SPECTRA; FLUX DENSITY; GALAXIES; IMAGES; LUMINOSITY; MAPS; RED SHIFT; SPACE; STARS; WAVELENGTHS

Citation Formats

Decarli, R., Walter, F., Hodge, J. A., Rix, H.-W., Schinnerer, E., Smail, I., Swinbank, A. M., Karim, A., Simpson, J. M., Chapman, S., Coppin, K. E. K., Cox, P., Dannerbauer, H., Greve, T. R., Ivison, R., Knudsen, K. K., Lindroos, L., Van der Werf, P., and Weiß, A., E-mail: decarli@mpia.de. An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies. United States: N. p., 2014. Web. doi:10.1088/0004-637X/780/2/115.
Decarli, R., Walter, F., Hodge, J. A., Rix, H.-W., Schinnerer, E., Smail, I., Swinbank, A. M., Karim, A., Simpson, J. M., Chapman, S., Coppin, K. E. K., Cox, P., Dannerbauer, H., Greve, T. R., Ivison, R., Knudsen, K. K., Lindroos, L., Van der Werf, P., & Weiß, A., E-mail: decarli@mpia.de. An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies. United States. doi:10.1088/0004-637X/780/2/115.
Decarli, R., Walter, F., Hodge, J. A., Rix, H.-W., Schinnerer, E., Smail, I., Swinbank, A. M., Karim, A., Simpson, J. M., Chapman, S., Coppin, K. E. K., Cox, P., Dannerbauer, H., Greve, T. R., Ivison, R., Knudsen, K. K., Lindroos, L., Van der Werf, P., and Weiß, A., E-mail: decarli@mpia.de. Fri . "An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies". United States. doi:10.1088/0004-637X/780/2/115.
@article{osti_22348269,
title = {An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies},
author = {Decarli, R. and Walter, F. and Hodge, J. A. and Rix, H.-W. and Schinnerer, E. and Smail, I. and Swinbank, A. M. and Karim, A. and Simpson, J. M. and Chapman, S. and Coppin, K. E. K. and Cox, P. and Dannerbauer, H. and Greve, T. R. and Ivison, R. and Knudsen, K. K. and Lindroos, L. and Van der Werf, P. and Weiß, A., E-mail: decarli@mpia.de},
abstractNote = {We study the sub-millimeter properties of color-selected galaxies via a stacking analysis applied for the first time to interferometric data at sub-millimeter wavelengths. We base our study on 344 GHz ALMA continuum observations of ∼20''-wide fields centered on 86 sub-millimeter sources detected in the LABOCA Extended Chandra Deep Field South (ECDFS) Sub-millimeter Survey. We select various classes of galaxies (K-selected, star-forming sBzK galaxies, extremely red objects, and distant red galaxies) according to their optical/near-infrared fluxes. We find clear, >10σ detections in the stacked images of all these galaxy classes. We include in our stacking analysis Herschel/SPIRE data to constrain the dust spectral energy distribution of these galaxies. We find that their dust emission is well described by a modified blackbody with T {sub dust} ≈ 30 K and β = 1.6 and infrared luminosities of (5-11) × 10{sup 11} L {sub ☉} or implied star formation rates of 75-140 M {sub ☉} yr{sup –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 sub-mm 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.},
doi = {10.1088/0004-637X/780/2/115},
journal = {Astrophysical Journal},
number = 2,
volume = 780,
place = {United States},
year = {Fri Jan 10 00:00:00 EST 2014},
month = {Fri Jan 10 00:00:00 EST 2014}
}
  • The large gas and dust reservoirs of submillimeter galaxies (SMGs) could potentially provide ample fuel to trigger an active galactic nucleus (AGN), but previous studies of the AGN fraction in SMGs have been controversial largely due to the inhomogeneity and limited angular resolution of the available submillimeter surveys. Here we set improved constraints on the AGN fraction and X-ray properties of the SMGs with Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra observations in the Extended Chandra Deep Field-South (E-CDF-S). This study is the first among similar works to have unambiguously identified the X-ray counterparts of SMGs; this is accomplished usingmore » the fully submillimeter-identified, statistically reliable SMG catalog with 99 SMGs from the ALMA LABOCA E-CDF-S Submillimeter Survey. We found 10 X-ray sources associated with SMGs (median redshift z = 2.3), of which eight were identified as AGNs using several techniques that enable cross-checking. The other two X-ray detected SMGs have levels of X-ray emission that can be plausibly explained by their star formation activity. Six of the eight SMG-AGNs are moderately/highly absorbed, with N {sub H} > 10{sup 23} cm{sup –2}. An analysis of the AGN fraction, taking into account the spatial variation of X-ray sensitivity, yields an AGN fraction of 17{sub −6}{sup +16}% for AGNs with rest-frame 0.5-8 keV absorption-corrected luminosity ≥7.8 × 10{sup 42} erg s{sup –1}; we provide estimated AGN fractions as a function of X-ray flux and luminosity. ALMA's high angular resolution also enables direct X-ray stacking at the precise positions of SMGs for the first time, and we found four potential SMG-AGNs in our stacking sample.« less
  • We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z {sub phot} = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distributionmore » comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z {sub phot} = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M {sub *} = (8 ± 1) × 10{sup 10} M {sub ☉}, although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M{sub H} distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.« less
  • 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 {sub 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}),more » and 0.43 {+-} 0.04 mJy (10.8{sigma}) for the K {sub 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 {approx_equal} 1-2, this implies an average far-IR luminosity of {approx}(1-5) x 10{sup 11} L{sub sun} and star formation rate (SFR) of {approx}20-90 M{sub sun} . 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 {sub vega} {<=} 20 galaxies are found to contribute 7.27 {+-} 0.34 Jy deg{sup -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{sup -2} (3.4% {+-} 1.3%) and 0.20 {+-} 0.14 Jy deg{sup -2} (0.5% {+-} 0.3%) to the EBL. We present the first delineation of the average submm signal from the K {sub 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 {approx}2-3 from z {approx} 2 to z {approx} 0. This is in line with a cosmic star formation history in which the star formation activity in galaxies increases significantly at z {approx}> 1. A linear correlation between the average 24 {mu}m and 870 {mu}m flux densities is found for the K {sub vega} {<=} 20 galaxies with 24 {mu}m fluxes {approx}<350 {mu}Jy (corresponding to L {sub IR} {approx_equal} 1.5 x 10{sup 12} L{sub sun} at z {approx_equal} 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 L {sub IR} {approx}< 1.5 x 10{sup 12} L{sub sun} 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.« less
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  • We analyze Hubble Space Telescope WFC3/H {sub 160}-band observations of a sample of 48 Atacama Large Millimeter/submillimeter Array detected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South field, to study their stellar morphologies and sizes. We detect 79% ± 17% of the SMGs in the H {sub 160}-band imaging with a median sensitivity of 27.8 mag, and most (80%) of the nondetections are SMGs with 870 μm fluxes of S {sub 870} < 3 mJy. With a surface brightness limit of μ {sub H} ∼ 26 mag arcsec{sup –2}, we find that 82% ± 9% of the Hmore » {sub 160}-band-detected SMGs at z = 1-3 appear to have disturbed morphologies, meaning they are visually classified as either irregulars or interacting systems, or both. By determining a Sérsic fit to the H {sub 160} surface brightness profiles, we derive a median Sérsic index of n = 1.2 ± 0.3 and a median half-light radius of r{sub e} = 4.4{sub −0.5}{sup +1.1} kpc for our SMGs at z = 1-3. We also find significant displacements between the positions of the H {sub 160} component and 870 μm emission in these systems, suggesting that the dusty starburst regions and less-obscured stellar distribution are not colocated. We find significant differences in the sizes and the Sérsic index between our z = 2-3 SMGs and z ∼ 2 quiescent galaxies, suggesting that a major transformation of the stellar light profile is needed in the quenching processes if SMGs are progenitors of the red-and-dead z ∼ 2 galaxies. Given the short-lived nature of SMGs, we postulate that the majority of the z = 2-3 SMGs with S {sub 870} ≳ 2 mJy are early/mid-stage major mergers.« less