ABSTRACT
We have used ALMA and NOEMA to study the molecular gas reservoirs in 61 ALMA-identified submillimetre galaxies (SMGs) in the COSMOS, UDS, and ECDFS fields. We detect 12CO ($J_{\rm up} =$ ...2–5) emission lines in 50 sources, and C i(3P1 − 3P0) emission in eight, at $z =$ 1.2–4.8 and with a median redshift of 2.9 ± 0.2. By supplementing our data with literature sources, we construct a statistical CO spectral line energy distribution and find that the 12CO line luminosities in SMGs peak at Jup ∼ 6, consistent with similar studies. We also test the correlations of the CO, C i, and dust as tracers of the gas mass, finding the three to correlate well, although the CO and dust mass as estimated from the 3-mm continuum are preferable. We estimate that SMGs lie mostly on or just above the star-forming main sequence, with a median gas depletion timescale, tdep = Mgas/SFR, of 210 ± 40 Myr for our sample. Additionally, tdep declines with redshift across z ∼ 1–5, while the molecular gas fraction, μgas = Mgas/M*, increases across the same redshift range. Finally, we demonstrate that the distribution of total baryonic mass and dynamical line width, Mbaryon–σ, for our SMGs is consistent with that followed by early-type galaxies in the Coma cluster, providing strong support to the suggestion that SMGs are progenitors of massive local spheroidal galaxies. On the basis of this, we suggest that the SMG populations above and below an 870-μm flux limit of S870 ∼ 5 mJy may correspond to the division between slow and fast rotators seen in local early-type galaxies.
ABSTRACT
We analyse a robust sample of 30 near-infrared-faint (KAB > 25.3, 5σ) submillimetre galaxies (SMGs) selected from a 0.96 deg2 field to investigate their properties and the cause of their ...faintness in optical/near-infrared wavebands. Our analysis exploits precise identifications based on Atacama Large Millimeter Array (ALMA) 870-μm continuum imaging, combined with very deep near-infrared imaging from the UKIDSS Ultra Deep Survey. We estimate that SMGs with KAB > 25.3 mag represent 15 ± 2 per cent of the total population brighter than S870 = 3.6 mJy, with a potential surface density of ∼450 deg−2 above S870 ≥ 1 mJy. As such, they pose a source of contamination in surveys for both high-redshift ‘quiescent’ galaxies and very high redshift Lyman-break galaxies. We show that these K-faint SMGs represent the tail of the broader submillimetre population, with comparable dust and stellar masses to KAB ≤ 25.3 mag SMGs, but lying at significantly higher redshifts (z = 3.44 ± 0.06 versus z = 2.36 ± 0.11) and having higher dust attenuation (AV = 5.2 ± 0.3 versus AV = 2.9 ± 0.1). We investigate the origin of the strong dust attenuation and find indications that these K-faint galaxies have smaller dust continuum sizes than the KAB ≤ 25.3 mag galaxies, as measured by ALMA, which suggests their high attenuation is related to their compact sizes. We identify a correlation of dust attenuation with star formation rate surface density (ΣSFR), with the K-faint SMGs representing the higher ΣSFR and highest AV galaxies. The concentrated, intense star formation activity in these systems is likely to be associated with the formation of spheroids in compact galaxies at high redshifts, but as a result of their high obscuration these galaxies are completely missed in ultraviolet, optical, and even near-infrared surveys.
ABSTRACT
We present an ALMA study of the ∼180 brightest sources in the SCUBA-2 850-μm map of the COSMOS field from the S2COSMOS survey, as a pilot study for AS2COSMOS – a full survey of the ∼1000 ...sources in this field. In this pilot study, we have obtained 870-μm continuum maps of an essentially complete sample of the brightest 182 sub-millimetre sources ($S_{850\, \mu \rm m}\gt $ 6.2 mJy) in COSMOS. Our ALMA maps detect 260 sub-millimetre galaxies (SMGs) spanning a range in flux density of $S_{870\, \mu \rm m}$ = 0.7–19.2 mJy. We detect more than one SMG counterpart in 34 ± 2 per cent of sub-millimetre sources, increasing to 53 ± 8 per cent for SCUBA-2 sources brighter than $S_{850\, \mu \rm m}\gt $ 12 mJy. We estimate that approximately one-third of these SMG–SMG pairs are physically associated (with a higher rate for the brighter secondary SMGs, $S_{870\, \mu \rm m}\gtrsim$ 3 mJy), and illustrate this with the serendipitous detection of bright C ii 157.74-μm line emission in two SMGs, AS2COS 0001.1 and 0001.2 at z = 4.63, associated with the highest significance single-dish source. Using our source catalogue, we construct the interferometric 870-μm number counts at $S_{870\, \mu \rm m}\gt $ 6.2 mJy. We use the extensive archival data of this field to construct the multiwavelength spectral energy distribution of each AS2COSMOS SMG, and subsequently model this emission with magphys to estimate their photometric redshifts. We find a median photometric redshift for the $S_{870\, \mu \rm m}\gt $ 6.2 mJy AS2COSMOS sample of z = 2.87 ± 0.08, and clear evidence for an increase in the median redshift with 870-μm flux density suggesting strong evolution in the bright end of the 870-μm luminosity function.
ABSTRACT
We present an analysis of the spatial clustering of a large sample of high-resolution, interferometically identified, submillimetre galaxies (SMGs). We measure the projected ...cross-correlation function of ∼350 SMGs in the UKIDSS Ultra Deep-Survey Field across a redshift range of z = 1.5–3 utilizing a method that incorporates the uncertainties in the redshift measurements for both the SMGs and cross-correlated galaxies through sampling their full probability distribution functions. By measuring the absolute linear bias of the SMGs, we derive halo masses of $\log _{10}(M_{\rm halo}{h^{-1}\, \rm M_{\odot }})$ ∼ 12.8 with no evidence of evolution in the halo masses with redshift, contrary to some previous work. From considering models of halo mass growth rates, we predict that the SMGs will reside in haloes of mass $\log _{10}(M_{\rm halo}{h^{-1}\, \rm M_{\odot }})$ ∼ 13.2 at z = 0, consistent with the expectation that the majority of z = 1.5–3 SMGs will evolve into present-day spheroidal galaxies. Finally, comparing to models of stellar-to-halo mass ratios, we show that SMGs may correspond to systems that are maximally efficient at converting their gas reservoirs into stars. We compare them to a simple model for gas cooling in haloes that suggests that the unique properties of the SMG population, including their high levels of star formation and their redshift distribution, are a result of the SMGs being the most massive galaxies that are still able to accrete cool gas from their surrounding intragalactic medium.
We have obtained deep 1 and 3 mm spectral-line scans towards a candidate z ≳ 5 ALMA-identified AzTEC submillimetre galaxy (SMG) in the Subaru/XMM-Newton Deep Field (or UKIDSS UDS), ASXDF1100.053.1, ...using the NOrthern Extended Millimeter Array (NOEMA), aiming to obtain its spectroscopic redshift. ASXDF1100.053.1 is an unlensed optically dark millimetre-bright SMG with S1100 μm = 3.5 mJy and KAB > 25.7 (2σ), which was expected to lie at z = 5–7 based on its radio–submillimetre photometric redshift. Our NOEMA spectral scan detected line emission due to 12CO(J = 5–4) and (J = 6–5), providing a robust spectroscopic redshift, zCO = 5.2383 ± 0.0005. Energy-coupled spectral energy distribution modelling from optical to radio wavelengths indicates an infrared luminosity LIR = 8.3−1.4+1.5 × 1012 L⊙, a star formation rate SFR = 630−380+260 M⊙ yr−1, a dust mass Md = 4.4−0.3+0.4 × 108 M⊙, a stellar mass Mstellar = 3.5−1.4+3.6 × 1011 M⊙, and a dust temperature Td = 37.4−1.8+2.3 K. The CO luminosity allows us to estimate a gas mass Mgas = 3.1 ± 0.3 × 1010 M⊙, suggesting a gas-to-dust mass ratio of around 70, fairly typical for z ∼ 2 SMGs. ASXDF1100.053.1 has ALMA continuum size Re = 1.0−0.1+0.2 kpc, so its surface infrared luminosity density ΣIR is 1.2−0.2+0.1 × 1012 L⊙ kpc−2. These physical properties indicate that ASXDF1100.053.1 is a massive dusty star-forming galaxy with an unusually compact starburst. It lies close to the star-forming main sequence at z ∼ 5, with low Mgas/Mstellar = 0.09, SFR/SFRMS(RSB) = 0.6, and a gas-depletion time τdep of ≈50 Myr, modulo assumptions about the stellar initial mass function in such objects. ASXDF1100.053.1 has extreme values of Mgas/Mstellar, RSB, and τdep compared to SMGs at z ∼ 2–4, and those of ASXDF1100.053.1 are the smallest among SMGs at z > 5. ASXDF1100.053.1 is likely a late-stage dusty starburst prior to passivisation. The number of z = 5.1–5.3 unlensed SMGs now suggests a number density dN/dz = 30.4 ± 19.0 deg−2, barely consistent with the latest cosmological simulations.
Abstract
We report the discovery of a 10 comoving megaparsec (cMpc)-scale structure traced by massive submillimeter galaxies (SMGs) at
z
∼ 4.6. These galaxies are selected from an emission line ...search of ALMA Band 7 observations targeting 184 luminous submillimeter sources (
S
850
μ
m
≥ 6.2 mJy) across 1.6 degrees
2
in the COSMOS field. We identify four C
ii
emitting SMGs and two probable C
ii
emitting SMG candidates at
z
= 4.60–4.64 with velocity-integrated signal-to-noise ratio of S/N > 8. Four of the six emitters are near-infrared blank SMGs. After excluding one SMG whose emission line is falling at the edge of the spectral window, all galaxies show clear velocity gradients along the major axes that are consistent with rotating gas disks. The estimated rotation velocities of the disks are 330–550 km s
−1
and the inferred host dark-matter halo masses are ∼2–8 × 10
12
M
⊙
. From their estimated halo masses and C
ii
luminosity function, we suggest that these galaxies have a high (50%–100%) duty cycle and high (∼0.1) baryon conversion efficiency (SFR relative to baryon accretion rate), and that they contribute ≃2% to the total star formation rate density at
z
= 4.6. These SMGs are concentrated within just 0.3% of the full survey volume, suggesting they are strongly clustered. The extent of this structure and the individual halo masses suggest that these SMGs will likely evolve into members of a ∼10
15
M
⊙
cluster at
z
= 0. This survey reveals a synchronized dusty starburst in massive halos at
z
> 4, which could be driven by mergers or fed by smooth gas accretion.
ABSTRACT We report the results of 1 5 × 3′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array toward the central region of the z = 3.09 SSA22 protocluster. By combining our ...source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S1.1 mm = 0.7-6.4 mJy (LIR ∼ 1012.1-1013.1 L ) are at z = 3.08-3.10. Not only are these SMGs members of the protocluster, but they in fact reside within the node at the junction of the 50 Mpc scale filamentary three-dimensional structure traced by Ly emitters in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 M yr−1 Mpc−3 in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host an X-ray-luminous active galactic nucleus. Our results suggest that the vigorous star formation activity and the growth of supermassive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Ly blobs, implying that the two populations coexist in high-density environments for a few cases.
We present the results from a 1.1-mm imaging survey of the SSA22 field, known for having an overdensity of z = 3.1 Lyman α emitting galaxies (LAEs), taken with the astronomical thermal emission ...camera (AzTEC) on the Atacama Submillimeter Telescope Experiment (ASTE). We imaged a 950-arcmin2 field down to a 1σ sensitivity of 0.7–1.3 mJy beam−1 to find 125 submillimetre galaxies (SMGs) with a signal-to-noise ratio ≥3.5. Counterpart identification using radio and near/mid-infrared data was performed and one or more counterpart candidates were found for 59 SMGs. Photometric redshifts based on optical to near-infrared images were evaluated for 45 of these SMGs with Spitzer/IRAC data and the median value is found to be z = 2.4. By combining these estimations with estimates from the literature, we determined that 10 SMGs might lie within the large-scale structure at z = 3.1. The two-point angular cross-correlation function between LAEs and SMGs indicates that the positions of the SMGs are correlated with the z = 3.1 protocluster. These results suggest that the SMGs were formed and evolved selectively in the high dense environment of the high-redshift Universe. This picture is consistent with the predictions of the standard model of hierarchical structure formation.
We quantify the fraction of the cosmic infrared background (CIB) that originates from galaxies identified in the UV/optical/near-infrared by stacking 81,250 (~35.7 arcmin super(-2)) K-selected ...sources (K sub(AB) < 24.0) split according to their rest-frame U - V versus V - J colors into 72,216 star-forming and 9034 quiescent galaxies, on maps from Spitzer/MIPS (24 mu m), Herschel/PACS (100, 160 mu m), Herschel/SPIRE (250, 350, 500 mu m), and AzTEC (1100 mu m). Of that total, about 95% originates from star-forming galaxies, while the remaining 5% is from apparently quiescent galaxies. The CIB at lambda lap 200 mu m appears to be sourced predominantly from galaxies at z lap 1, while at lambda gap 200 mu the bulk originates from 1 lap z lap 2. Stacking analyses were performed using simstack, a novel algorithm designed to account for possible biases in the stacked flux density due to clustering. It is made available to the public at www.astro.caltech.edu/~viero/viero_homepage/toolbox.html.
Background
Previously, the mucosal histology in achalasia has only been investigated using superficial biopsy or surgically resected esophageal specimens in end‐stage cases. We investigated the ...histology of the full‐layer mucosa in early and advanced achalasia.
Methods
Endoscopy was performed for the pinstripe pattern (PSP) (an early achalasia indicator) and dilation and thickening of the mucosa (advanced achalasia indicators). A mucosal entry site for peroral endoscopic myotomy was created using cap‐fitted endoscopic mucosal resection to access the full‐layer mucosa and the submucosa.
Key Results
Mucosal histology was compared between 32 patients with achalasia and 15 controls. Histological esophagitis with findings of inflammatory cell infiltration and dilated intercellular spaces was observed more in patients with achalasia than in controls (87.5% vs 13.3%, P<.001; 84.4% vs 46.7%, P=.049). Muscularis mucosae (MM) atrophy and epithelial wave were only observed in achalasia (40.6% vs 0%, P=.005; 28.1% vs 0%, P=.043). Fibrosis was more common in achalasia, but without statistical significance (31.3% vs 20.0%, P=.503). In achalasia with endoscopic dilation and thickening of the mucosa, MM atrophy was observed histologically, and in cases involving endoscopic PSP, the histological epithelial wave was observed.
Conclusions & Inferences
Histological findings of esophagitis were observed endoscopically even in early achalasia. Pinstripe pattern corresponds to the epithelial wave observed histologically in achalasia, whereas endoscopic findings in advanced achalasia correspond to MM atrophy. Appropriate management is necessary during early achalasia to prevent progression to advanced achalasia with more severe histological changes.
The pinstripe pattern on endoscopy corresponds to histological epithelial wave, and endoscopic findings of advanced achalasia are related to histological muscularis mucosae atrophy. Appropriate management is necessary during early achalasia to prevent progression to advanced achalasia with more severe histological changes.
PDF
![FIR-luminous [C ii] Emitter...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X_1538-4357/small "FIR-luminous [C ii] Emitters in the ALMA-SCUBA-2 COSMOS Survey (AS2COSMOS): The Nature of Submillimeter Galaxies in a 10 Comoving Megaparsec-scale Structure at z ∼ 4.6")
