Ever since the initial measurements of the cosmic infrared background (CIB; for a review, see Hauser & Dwek 2001) revealed that the amount of energy radiated in the far-infrared (IR) and submillimeter spectral windows is comparable to that measured at ultraviolet (UV) and optical wavelengths, it has been widely recognized that one of the keys to a comprehensive understanding of the star formation history of the universe is the study of the multiwavelength properties of dusty star-forming galaxies (DSFGs), whose integrated radiation produces the CIB. These systems host intense star-forming activity obscured by large columns of dust, which re-emit the UV radiation of young hot stars at longer wavelengths, so that the peak of their rest-frame spectral energy distribution (SED) falls in the far-IR. In the local universe, DSFGs are typically identified as luminous or ultraluminous infrared galaxies (LIRGs/ULIRGs; Sanders & Mirabel 1996), whereas more distant DSFGs’ emission can be redshifted into the submillimeter domain, allowing many to manifest as submillimeter galaxies (SMGs; Blain et al. 2002; Casey et al. 2014). SMGs were first detected with the Submillimeter Common-User Bolometer Array (SCUBA; Holland et al. 1999) on the James Clerk Maxwell Telescope both in blank-field surveys (e.g., Hughes et al. 1998; Barger et al. 1999; Scott et al. 2002; Serjeant et al. 2003; Webb et al. 2003; Coppin et al. 2006) and behind galaxy clusters (e.g., Smail et al. 1997; Chapman et al. 2002; Cowie et al. 2002; Knudsen et al. 2008). With the subsequent advent of comparable single-dish telescopes and larger format instruments covering the 870 μm atmospheric window like the Large APEX Bolometer Camera (LABOCA; Siringo et al. 2009) on the 12 m Atacama Pathfinder Experiment telescope (APEX; Güsten et al. 2006), and more recently SCUBA-2 (Holland et al. 2013), the number of known SMGs is now of the order of a few thousand (e.g., Weiß et al. 2009; Johansson et al. 2011; Chen et al. 2013; Hsu et al. 2016; Geach et al. 2017), and intensive observational efforts have been devoted to understanding their physical properties. In this quest, one of the main challenges has been the coarse (15″–20″) resolution of single-dish observations, which hinders the identification of counterparts at different wavelengths and can result in the blending of multiple, fainter SMGs into a single brighter object. However, the persistence of the local radio–FIR correlation to higher redshifts (e.g., Condon 1992) allows accurate SMG positions from deep radio imaging obtained with the Very Large Array (VLA) at 1.4 GHz and the Australia Telescope Compact Array (ATCA) at 2.1 GHz (e.g., Ivison et al. 1998, 2000, 2002; Smail et al. 2000; Chapman et al. 2002) to be determined, thus enabling the identification of optical and near-IR counterparts, determination of photometric and spectroscopic redshifts (e.g., Chapman et al. 2005), modeling of SEDs, analysis of individual morphologies, and characterization of dust and stellar components (for full reviews of these results, see Blain et al. 2002 and Casey et al. 2014). The general picture derived from such studies is that SMGs are massive, gas-rich galaxies with high IR luminosities (





) and complex optical/near-IR morphologies, in which respects they resemble the local ULIRG population. However, SMGs have a median redshift z ∼ 2.5 (Chapman et al. 2005) and a significantly higher number density than ULIRGs. Complementary observations with centimeter and (sub)millimeter telescopes have been used as well to study the cool, molecular gas of SMGs (e.g., Carilli & Walter 2013), an effort that has been transformed in recent years thanks to the exceptional spatial resolution and sensitivity provided by the Jansky VLA and the Atacama Large Millimeter/submillimeter Array (ALMA). Moreover, high-resolution continuum imaging at 870 μm with ALMA has made it possible to resolve the structure of the dust emission from SMGs and identify their counterparts in an unbiased way, revealing that a large fraction of bright single-dish detections actually “break up” into multiple, fainter (





 mJy) SMGs blended together at the coarse resolution of the maps in which they were detected (Hodge et al. 2013; Karim et al. 2013; Simpson et al. 2015a, 2015b).
Citation: Hsu et al. 2016
Citation function: Background; Background