Abstract
Submillimeter/millimeter observations of dusty star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA) have shown that dust continuum emission generally occurs in compact regions smaller than the stellar distribution. However, it remains to be understood how systematic these findings are. Studies often lack homogeneity in the sample selection, target discontinuous areas with inhomogeneous sensitivities, and suffer from modest uv coverage coming from single array configurations. GOODS-ALMA is a 1.1 mm galaxy survey over a continuous area of 72.42 arcmin2 at a homogeneous sensitivity. In this version 2.0, we present a new low resolution dataset and its combination with the previous high resolution dataset from the survey, improving the uv coverage and sensitivity reaching an average of σ = 68.4 μJy beam−1. A total of 88 galaxies are detected in a blind search (compared to 35 in the high resolution dataset alone), 50% at S/Npeak ≥ 5 and 50% at 3.5 ≤ S/Npeak ≤ 5 aided by priors. Among them, 13 out of the 88 are optically dark or faint sources (H- or K-band dropouts). The sample dust continuum sizes at 1.1 mm are generally compact, with a median effective radius of Re = 0.″10 ± 0.″05 (a physical size of Re = 0.73 ± 0.29 kpc at the redshift of each source). Dust continuum sizes evolve with redshift and stellar mass resembling the trends of the stellar sizes measured at optical wavelengths, albeit a lower normalization compared to those of late-type galaxies. We conclude that for sources with flux densities S1.1 mm > 1 mJy, compact dust continuum emission at 1.1 mm prevails, and sizes as extended as typical star-forming stellar disks are rare. The S1.1 mm < 1 mJy sources appear slightly more extended at 1.1 mm, although they are still generally compact below the sizes of typical star-forming stellar disks.
Highlights
Galaxies luminous in the infrared (IR) and submillimeter/millimeter wavelengths are intense starforming systems, some of which constitute the most powerful starbursts in the universe
From the first samples of mid-IR and far-IR bright galaxies uncovered by the IRAS satellite (e.g., Neugebauer et al 1984; Rowan-Robinson et al 1984; Elbaz et al 1992) and the SCUBA bolometer at submm wavelengths (e.g., Smail et al 1997; Hughes et al 1998; Barger et al 1998), the Atacama Large Millimeter/submillimeter array (ALMA) has recently opened a new era in the studies of dusty starforming galaxies (DSFGs)
There are examples of observations of more extended galaxy-wide dust continuum emission (e.g., Rujopakarn et al 2016; Cheng et al 2020; Sun et al 2021; Cochrane et al 2021) and simulations indicating that differential attenuation could play an important role in how observations compare the extent of the dust continuum emission to that of the stars (Popping et al 2021)
Summary
Galaxies luminous in the infrared (IR) and submillimeter/millimeter (submm/mm) wavelengths are intense starforming systems, some of which constitute the most powerful starbursts in the universe. There are examples of observations of more extended galaxy-wide dust continuum emission (e.g., Rujopakarn et al 2016; Cheng et al 2020; Sun et al 2021; Cochrane et al 2021) and simulations indicating that differential attenuation could play an important role in how observations compare the extent of the dust continuum emission to that of the stars (Popping et al 2021) It remains to be understood how systematic compactness is in DSFGs. Many ALMA studies have been biased to follow-ups of galaxy samples, often targeting discontinuous areas and with inhomogeneous sensitivities. When magnitudes are quoted they are in the AB system (Oke 1974)
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