An ALMA survey of submillimetre galaxies in the Extended Chandra Deep Field South: high-resolution 870 μm source counts

By A. Karim, M. Swinbank, J. Hodge, I. Smail, F. Walter, A. Biggs, J. Simpson, A. Danielson, D. M. Alexander, F. Bertoldi and 26 more. 2012

221 citations recorded by the source corpus.

We report the first counts of faint submillimetre galaxies (SMGs) in the 870-mu m band derived from arcsecond-resolution observations with the Atacama Large Millimeter Array (ALMA). We have used ALMA to map a sample of 122 870-mu m-selected submillimetre sources drawn from the 0 degrees.5x0 degrees.5 the Large Apex BOlometer CAmera (LABOCA) Extended Chandra Deep Field South submillimetre survey (LESS). These ALMA maps have an average depth of sigma 870(mu m) similar to 0.4 mJy, some approximately three times deeper than the original LABOCA survey and critically the angular resolution is more than an order of magnitude higher, FWHM of similar to 1.5 arcsec compared to similar to 19 arcsec for the LABOCA discovery map. This combination of sensitivity and resolution allows us to precisely pinpoint the SMGs contributing to the submillimetre sources from the LABOCA map, free from the effects of confusion. We show that our ALMA-derived SMG counts broadly agree with the submillimetre source counts from previous, lower resolution single-dish surveys, demonstrating that the bulk of the submillimetre sources are not caused by blending of unresolved SMGs. The difficulty which well-constrained theoretical models have in reproducing the high surface densities of SMGs, thus remains. However, our observations do show that all of the very brightest sources in the LESS sample, S-870 (mu m) greater than or similar to 12 mJy, comprise emission from multiple, fainter SMGs, each with 870-mu m fluxes of less than or similar to 9 mJy. This implies a natural limit to the star formation rate in SMGs of less than or similar to 10(3) M-circle dot yr(-1), which in turn suggests that the space densities of z > 1 galaxies with gas masses in excess of similar to 5 x 10(10) M-circle dot is <10(-5) Mpc(-3). We also discuss the influence of this blending on the identification and characterization of the SMG counterparts to these bright submillimetre sources and suggest that it may be responsible for previous claims that they lie at higher redshifts than fainter SMGs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9596713752bed5df13df05903761cd68752435bc

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Citations in the corpus

The dust content of galaxies from z = 0 to z = 9 (2016, background): “High spatial resolution observations with ALMA have suggested that the brightest sub-mm sources in such surveys consist of multiple lower luminosity objects, blended within one large beam (Karim et al. 2013; Hayward et al. 2013a).”
A SUBSTANTIAL POPULATION OF MASSIVE QUIESCENT GALAXIES AT z ∼ 4 FROM ZFOURGE (2013, background): “Based on the 870 μm source counts of Karim et al. (2013), and tentatively assuming that 10% are at z > 4 (e.g., Swinbank et al. 2012), we find that obscured starbursting galaxies are sufficiently numerous.”
How sensitive are predicted galaxy luminosities to the choice of stellar population synthesis model (2013, background): “We ﬁnd that both the number counts and redshift distribution of model 870 µ m sources are virtually indistin-guishible from those at 850 µ m. Observations from ALMA by Karim et al. (2013) at 870 µ m have shown that the number counts of bright sources are aﬀected by the confusion of sources, and thus”
An ALMA survey of the SCUBA-2 CLS UDS field: physical properties of 707 sub-millimetre galaxies (2019, methodology): “The first ALMA follow-up of a single-dish sub-millimetre survey was the ALESS survey (Hodge et al. 2013; Karim et al. 2013) of a sample of 122 sources with S870 ≥ 3.5 mJy selected from the 0.25 deg2 LABOCA 870-μm map of the Extended Chandra Deep Field South (ECDFS) by Weiß et al. (2009).”
AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: THE REDSHIFT DISTRIBUTION AND EVOLUTION OF SUBMILLIMETER GALAXIES (2013, methodology): “Karim et al. (2013) and Hodge et al. (2013) propose this is due to the original LABOCA submm source fragmenting into a number of faint SMGs, and so we measure the number density and redshift distribution of 3.6µm sources in these “blank” maps and compare it to the redshift distribution in the field.”
KILOPARSEC-SCALE DUST DISKS IN HIGH-REDSHIFT LUMINOUS SUBMILLIMETER GALAXIES (2016, background): “…survey of single–dish 344 GHz LABOCA sources detected in the Extended Chandra Deep Field South (ECDFS) by Weiß et al. (2009), constituting the largest, most homogenous, and highest–sensitivity sample of interferometrically observed SMGs to date (ALESS; Hodge et al. 2013b; Karim et al. 2013).”
Characterization of Scuba-2 450 μm and 850 μm selected galaxies in the COSMOS field (2013, methodology): “…far-infrared interferometry is the only guaranteed method of identifying counterparts correctly (e.g. recent results from SMA, PdBI and ALMA targeting 850µm–1.1 mm sources; Younger et al. 2008; Wang et al. 2011; Barger et al. 2012; Smolčić et al. 2012; Karim et al. 2013; Hodge et al. 2013).”
AN ALMA SURVEY OF SUB-MILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: PHYSICAL PROPERTIES DERIVED FROM ULTRAVIOLET-TO-RADIO MODELING (2015, methodology): “122 of the 126 LESS sources were followed up at the same wavelength, with unprecedentedly high sensitivity and spatial resolution enabled by ALMA in the Cycle 0 program ALESS (Hodge et al. 2013; Karim et al. 2013).”
A deep ALMA image of the Hubble Ultra Deep Field (2016, background): “Most early ALMA programmes have focused (sensibly) on pointed observations of known objects (e.g. Hodge et al. 2013; Karim et al. 2013; Ouchi et al. 2013; Bussmann et al. 2015; Capak et al. 2015; Maiolino et al. 2015; Simpson et al. 2015a, 2015b; Scoville et al. 2016), including gravitationally…”
An ALMA survey of sub-millimetre Galaxies in the Extended Chandra Deep Field South: the far-infrared properties of SMGs (2013, methodology): “%) of the LABOCA sub-mm sources are resolved by ALMA into mul- tiple SMGs (see also Karim et al. 2013).”
Dusty Star Forming Galaxies at High Redshift (2014, methodology): “Although more recent follow-up of the Wardlow et al. sample indicate that some of the Laboca sources split intomultiples in ALMA imaging (Karim et al., 2013; Hodge et al., 2013b), the re-analysis of the population’s photometric redshifts with the high-resolution data (Simpson et al., 2013) find…”
GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5 (2013, background): “It is also possible that a Schechter function provides an inadequate description of the bright end shape of the number counts (e.g., if blending is not properly taken into account; see Fu et al. 2013; Ivison et al. 2013; Hodge et al. 2013; Karim et al. 2013).”
GOODS-ALMA: 1.1 mm galaxy survey (2018, background): “16, we compare our results with previous studies (Lindner et al. 2011; Scott et al. 2012; Karim et al. 2013; Hatsukade et al. 2013; Simpson et al. 2015b; Oteo et al. 2016; Hatsukade et al. 2016; Aravena et al. 2016; Fujimoto et al. 2016; Umehata et al. 2017; Geach et al. 2017; Dunlop et al. 2017).”