The Circumgalactic Medium of Submillimeter Galaxies. I. First Results From a Radio-Identified Sample

Abstract

We present the first results from an ongoing survey to characterize the circumgalactic medium (CGM) of massive high-redshift galaxies detected as submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG-QSO pairs with separations less than ∼36″ by cross-matching far-infrared-selected galaxies from Herschel with spectroscopically confirmed QSOs. The Herschel sources were selected to match the properties of the SMGs. We determined the sub-arcsecond positions of six Herschel sources with the Very Large Array and obtained secure redshift identification for three of those with near-infrared spectroscopy. The QSO sightlines probe transverse proper distances of 112, 157, and 198kpc at foreground redshifts of 2.043, 2.515, and 2.184, respectively, which are comparable to the virial radius of the ∼1013 M e halos expected to host SMGs. High-quality absorption-line spectroscopy of the QSOs reveals systematically strong H I Lyα absorption around all three SMGs, with rest-frame equivalent widths of ∼2-3Å. However, none of the three absorbers exhibit compelling evidence for optically thick H I gas or metal absorption, in contrast to the dominance of strong neutral absorbers in the CGM of luminous z∼2 QSOs. The low covering factor of optically thick H I gas around SMGs tentatively indicates that SMGs may not have as prominent cool gas reservoirs in their halos as the coeval QSOs and that they may inhabit less massive halos than previously thought.

An ALMA survey of submillimetre galaxies in the COSMOS field: Physical properties derived from energy balance spectral energy distribution modelling

“…Ivison et al 2000;Blain et al 2004;Aravena et al 2010;Hickox et al 2012;Miller et al 2015;Chen et al 2016b;Wilkinson et al 2017;Smolčić et al 2017a), merger incidence (e.g. Conselice et al 2003), and circumgalactic medium (Fu et al 2016). Regarding the intrinsic physical characteristics of SMGs, the properties studied so far include the sizes and morphologies (e.g.…”

The Strong Gravitationally Lensed Herschel Galaxy HLock01: Optical Spectroscopy Reveals a Close Galaxy Merger with Evidence of Inflowing Gas

“…If related with HLock01-R, it may suggest a substantial gas reservoir in the halo at an impact parameter of 110 kpc. It is worth noting that Fu et al (2016) used QSO absorption line spectroscopy in three high-z SMG-QSO close pairs, with the QSO at a larger redshift than the SMG, to probe the circumgalactic medium (CGM) at similar impact parameters. However, they did not find evidence of optically thick H I gas or strong neutral absorbers in the CGM.…”

The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 kpc

“…These apparent separations are likely different from the true separations based on ALMA images because of the significant positional uncertainty of SPIRE sources (Section 3.3). Refer to Fu et al (2016) for details about the parent sample. Finally, the ALMA targets in each of the three H-ATLAS/GAMA fields were selected to be located within a ∼10°diameter circle so that they can be observed in a single scheduling block (SB), optimizing the survey efficiency.…”

“…The 3.5 m space telescope has a resolution of FWHM=17 8 and 35 2 at 250 and 500 μm, respectively. Thus, the Herschel positions have large uncertainties: the positional offsets between Herschel sources and their Very Large Array (VLA) 6 GHz counterparts range between 2 7 and 7 9 (Fu et al 2016). Previous studies have used a matching radius of 3″-5″ to identify the far-IR counterparts of the optically selected QSOs (e.g., Cao Orjales et al 2012;Ma & Yan 2015;Dong & Wu 2016;Pitchford et al 2016).…”

“…(1) SMG-QSO composite galaxy-QSOs hosted by dusty starbursts (e.g., Guilloteau et al 1999;Wang et al 2013;Willott et al 2013;Trakhtenbrot et al 2017); (2) gas-rich mergers-SMG-QSO composite galaxies interacting with nearby dusty starbursts (e.g., Omont et al 1996;Carilli et al 2002;Clements et al 2009;Trakhtenbrot et al 2017); (3) gasrich−gas-poor mergers ("wet−dry" mergers)-QSOs with gaspoor hosts merging with nearby dusty starbursts (e.g., SMM J04135+10277 at z 2.84; = Riechers 2013); or (4) a line-of-sight projected SMG-QSO pair (e.g., SDSS J171209 +600144 at z 2.821; = Fu et al 2016). The last two categories appear to be the least common, with only one example in each category so far.…”