J/ApJS/282/40 First results from the Vz-GAL VLA Large Program (Prajapati+, 2026)
Vz-GAL: probing cold molecular gas in dusty star-forming galaxies at z=1-6.
Prajapati P., Riechers D., Cox P., Weiss A., Saintonge A., Jones B.,
Bakx T.J.L.C., Berta S., van der Werf P., Neri R., Butler K.M., Cooray A.,
Ismail D., Baker A.J., Borsato E., Harris A., Ivison R., Lehnert M.,
Marchetti L., Messias H., Omont A., Vlahakis C., Yang C.
<Astrophys. J. Suppl. Ser., 282, 40 (2026)>
=2026ApJS..282...40P 2026ApJS..282...40P
ADC_Keywords: Galaxies, IR; Redshifts; Radio lines; Carbon monoxide;
Interstellar medium; Surveys
Keywords: High-redshift galaxies ; Galaxy evolution ; Starburst galaxies ;
CO line emission ; Molecular gas ; Interstellar medium ;
Star formation
Abstract:
We present the first results of Vz-GAL, a high-redshift CO(J=1-0)
large survey with the Karl G. Jansky Very Large Array, targeting
92 Herschel-selected, infrared-luminous, dusty star-forming galaxies
at redshifts 1-6. These sources are selected based on having redshifts
and mid-/high-J CO transitions from the NOrthern Extended Millimeter
Array z-GAL survey. We successfully detect CO(J=1-0) emission in
90/92 galaxies at the expected positions and redshifts, including nine
tentative detections at 2σ-3σ significance, and CO(J=2-1)
emission in 10 of these galaxies. The CO(J=1-0) luminosities suggest
apparent gas masses in the range
µMH2=(2-20)x1011(αCO/4.0)M☉, which implies gas
depletion times of 50-600Myr. These timescales show similar spread as
local ULIRGs, suggesting a self-regulatory mechanism that maintains a
consistent star formation rate per unit gas mass in starbursts across
redshifts. To quantify the contribution of "excitation correction"
factors to gas mass estimates, we calculate median CO line brightness
temperature ratios of r21=0.88±0.25, r31=0.61±0.22,
r41=0.49±0.15, r51=0.47±0.13, and r61=0.28±0.13.
Accounting for these corrections results in a reduced scatter in "gas
mass-star formation rate" relations. We also find a median
log(L'[CI](3P1-3^P0)/L'_CO(J=1-0))=-0.71±0.12 for a subsample of
23 sources, consistent with the ratios derived for local star-forming
galaxies. Together, our findings are in agreement with common
conditions in the cold gas reservoirs among star-forming galaxies over
a broad range in star formation modes, efficiencies, and scales.
Description:
Using the National Science Foundation (NSF)'s Karl G. Jansky Very
Large Array (VLA), a first study of the CO(1-0) emission in 14 dusty
star-forming galaxies (DSFGs) (VLA/20A-083; PI: Riechers) in the
redshift range 2<z<4, from the z-GAL pilot sample
(Neri+ 2020, J/A+A/635/A7), was conducted by
Stanley+ 2023ApJ...945...24S 2023ApJ...945...24S.
We here present the results of the continuation of this effort as a
VLA Large Program, Vz-GAL, to measure molecular gas in the entire
z-GAL sample as traced by CO(1-0) transition, and also observe
CO(2-1) for the z-GAL targets beyond z=3.6.
The observations presented here as part of the Vz-GAL large program
(VLA/23B-169 and VLA/25A-099; PI: Riechers) were carried out during
semesters 2023B and 2025A. In total, we observed 92/135 bright, dusty
galaxies with over 210hr of VLA integration time. Together with the
14 DSFGs from the pilot sample (Stanley+ 2023), this covers
106/135 z-GAL sources in CO(1-0) emission line and the underlying
continuum.
See Section 2.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 134 118 Vz-GAL (this work): CO(1-0) line and underlying
continuum properties, molecular gas masses, and
gas depletion times
table4.dat 90 10 Vz-GAL (this work): CO(2-1) line and underlying
continuum properties
table5.dat 113 14 Vz-GAL pilot program dusty star-forming galaxies
(DSFGs) from Stanley+ (2023ApJ...945...24S 2023ApJ...945...24S)
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See also:
VIII/103 : Herschel Multi-tiered Extragalactic Survey (Oliver+, 2012)
VIII/95 : Herschel Multi-tiered Extragalactic Survey (Oliver+, 2012)
J/ApJ/706/1364 : SINS survey of high-redshift gal. (Forster Schreiber+, 2009)
J/ApJ/719/763 : Millimeter-wave sources in the SPT survey (Vieira+, 2010)
J/A+A/532/A90 : PACS Evolutionary Probe (PEP-DR1) catalogs (Lutz+, 2011)
J/A+A/557/A66 : Effective SEDs of IR gal. at various z (Bethermin+, 2013)
J/ApJ/812/43 : ALMA 870um obs. of HerMES galaxies (Bussmann+, 2015)
J/ApJ/820/83 : ALMA galaxy properties in COSMOS field (Scoville+, 2016)
J/MNRAS/465/3558 : HATLAS candidate lensed galaxies (Negrello+, 2017)
J/ApJS/230/7 : Spectral flux densities from 50MHz to 50GHz (Perley+, 2017)
J/ApJS/233/22 : xCOLD GASS catalog (Saintonge+, 2017)
J/A+A/608/A144 : Strongly lensed submm galaxies CO spectra (Yang+, 2017)
J/MNRAS/473/1751 : Herschel Bright Sources (HerBS) (Bakx+, 2018)
J/A+A/628/A71 : CO spectra of 55 LIRGs and ULIRGs (Herrero-Illana+, 2019)
J/MNRAS/493/4276 : A search for the lenses in the HerBS sample (Bakx+, 2020)
J/A+A/635/A7 : NOEMA redshift of bright Herschel galaxies (Neri+, 2020)
J/ApJ/902/78 : ALMA 3mm new sp. redshifts for SPT galaxies (Reuter+, 2020)
J/A+A/641/A155 : CO+[CI] emission in distant galaxies (Valentino+, 2020)
J/A+A/646/A122 : NOEMA mm reduced data cubes of HerBS-89a (Berta+, 2021)
J/MNRAS/517/962 : Metal-rich galaxies dust, CO and [CI] (Dunne+, 2022)
J/ApJ/927/149 : Low-J CO line ratios for 152 CO map pairs (Leroy+, 2022)
J/MNRAS/510/2261 : H-ATLAS DR3 NIR counterparts in SGP field (Ward+, 2022)
J/A+A/678/A28 : z-GAL. III. Physical properties (Berta+, 2023)
J/A+A/678/A26 : z-GAL.I. Overview (Cox+, 2023)
J/A+A/678/A27 : z-GAL dust continuum properties (Ismail+, 2023)
http://vzgal.uni-koeln.de/ : Vz-GAL, a VLA Large Program homepage
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Source identifier
11- 15 A5 --- m_ID Component identifier within ID
16- 21 F6.4 --- zspec [1.37/5.4]? Z-GAL-based spectroscopic
redshift of galaxies
23 A1 --- l_Speak Limit flag on Speak
24- 28 F5.2 mJy Speak [0.2/3.63]? Peak flux density of
CO(1-0) line
30- 33 F4.2 mJy e_Speak [0.03/0.4]? Uncertainty in Speak
35- 38 I4 km/s DeltaV [148/1751]? FWHM line width of
CO(1-0) line
40- 42 I3 km/s e_DeltaV [16/490]? Uncertainty in DeltaV
44 A1 --- f_DeltaV [i] Flag on DeltaV (1)
46 A1 --- l_I Limit flag on I
47- 51 F5.2 Jy.km/s I [0.07/2.3]? Line flux of CO(1-0) line
53- 56 F4.2 Jy.km/s e_I [0.01/0.4]? Uncertainty in I
58 A1 --- l_muLCO Limit flag on muLCO
59- 62 F4.2 10+11K.km/s.pc2 muLCO [0.2/5.1]? Integrated line luminosity
of CO(1-0) line * gravitational
lensing factor
64- 67 F4.2 10+11K.km/s.pc2 e_muLCO [0.04/1.1]? Uncertainty in muLCO
69 A1 --- f_muLCO [l] Flag on muLCO (G1)
71 A1 --- l_muMass Limit flag on Mass
72- 76 F5.2 10+11Msun muMass [0.88/20.2]? Mass of molecular
hydrogen * gravitational lensing
factor (G4)
78- 81 F4.2 10+11Msun e_muMass [0.15/4.6]? Uncertainty in muMass
83 A1 --- f_muMass [l] Flag on Mass (G1)
85 A1 --- l_tau Limit flag on tau
86- 92 F7.2 Myr tau [19.7/704.2]? Gas depletion time
94- 99 F6.2 Myr e_tau [2/117.4]? Uncertainty in tau
101- 104 F4.1 GHz nuIF1 [15.9/48]? First intermediate
frequency band continuum central
frequency
106 A1 --- f_nuIF1 [*] Flag on nuIF1 (G2)
108- 111 F4.1 GHz nuIF2 [23/39.5]? Second intermediate
frequency band continuum central
frequency
113 A1 --- l_SIF1 Limit flag on SIF1
114- 118 F5.2 mJy SIF1 [0.02/1.2]? IF1 band continuum flux
density
120- 123 F4.2 mJy e_SIF1 [0.01/0.06]? Uncertainty in SIF1
125 A1 --- l_SIF2 Limit flag on SIF2
126- 130 F5.2 mJy SIF2 [0.04/0.4]? IF2 band continuum flux
density
132 A1 --- l_Sig Limit flag on Sig
133- 134 I2 --- Sig [2/13]? Line significance in σ;
rms noise of the moment-0 map of the
line
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Note (1): Flag as follows:
i = For non-detections (SNR<2) in CO(1-0), FWHM values are from z-GAL
mid-J CO-line results. The upper-limit on the CO(1-0) line flux of
HeLMS-44 has been derived using the linewidth from the
z-GAL CO(2-1) spectrum.
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Source identifier
11- 16 F6.4 --- zspec [3.7/5.4] Z-GAL-based spectroscopic
redshift of galaxies
18- 21 F4.2 mJy Speak [0.78/4.3] Peak flux density of
CO(2-1) line
23- 26 F4.2 mJy e_Speak Uncertainty in Speak
28- 30 I3 km/s DeltaV [288/691] FWHM line width of CO(2-1)
line
32- 34 I3 km/s e_DeltaV Uncertainty in DeltaV
36- 39 F4.2 Jy.km/s I [0.26/1.7] Line flux of CO(2-1) line
41- 44 F4.2 Jy.km/s e_I Uncertainty in I
46- 49 F4.2 10+11K.km/s.pc2 muLCO Integrated line luminosity of CO(2-1)
line * gravitational lensing factor
51- 54 F4.2 10+11K.km/s.pc2 e_muLCO ? Uncertainty in muLCO
56 A1 --- f_muLCO [l] Flag on muLCO (G1)
58- 61 F4.1 GHz nuIF1 First intermediate frequency band
continuum central frequency
63 A1 --- f_nuIF1 [*] Flag on nuIF1 (G2)
65- 68 F4.1 GHz nuIF2 ? Second intermediate frequency band
continuum central frequency
70 A1 --- l_SIF1 Limit flag on SIF1
72- 75 F4.2 mJy SIF1 IF1 band continuum flux density (G3)
77- 80 F4.2 mJy e_SIF1 ? Uncertainty in SIF1
82 A1 --- l_SIF2 Limit flag on SIF2
84- 87 F4.2 mJy SIF2 ? IF2 band continuum flux density (G3)
89- 90 I2 --- Sig Line significance in σ; rms
noise of the moment-0 map of the line
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Source identifier
11- 15 F5.3 --- zspec [2/4.1] Z-GAL-based spectroscopic
redshift of galaxies
17- 20 F4.2 mJy Speak [0.08/2.2] Peak flux density of
CO(1-0) line
22- 25 F4.2 mJy e_Speak Uncertainty in Speak
27- 30 I4 km/s DeltaV [197/1586]? FWHM line width of
CO(1-0) line
32- 34 I3 km/s e_DeltaV Uncertainty in DeltaV
36- 40 F5.3 Jy.km/s I [0.06/1.1]? Line flux of CO(1-0) line
42- 46 F5.3 Jy.km/s e_I Uncertainty in I
48- 50 F3.1 10+11K.km/s.pc2 muLCO Integrated line luminosity of CO(1-0)
line * gravitational lensing factor
52- 54 F3.1 10+11K.km/s.pc2 e_muLCO Uncertainty in muLCO
56 A1 --- f_muLCO [l] Flag on muLCO (1)
58- 61 F4.1 10+11Msun muMass Mass of molecular hydrogen *
gravitational lensing factor (G4)
63- 65 F3.1 10+11Msun e_muMass Uncertainty in muMass
67 A1 --- f_muMass [l] Flag on muMass (1)
69- 71 I3 Myr tau Gas depletion time
73- 75 I3 Myr e_tau Uncertainty in tau
77- 80 F4.1 GHz nuIF1 First intermediate frequency band
continuum central frequency
82- 85 F4.1 GHz nuIF2 ? Second intermediate frequency band
continuum central frequency
87 A1 --- l_SIF1 Limit flag on SIF1
89- 93 F5.3 mJy SIF1 IF1 band continuum flux density (G3)
95- 99 F5.3 mJy e_SIF1 ? Uncertainty in SIF1
101 A1 --- l_SIF2 Limit flag on SIF2
103- 106 F4.2 mJy SIF2 ? IF2 band continuum flux density (G3)
108- 111 F4.2 mJy e_SIF2 ? Uncertainty in SIF2
113 I1 --- Sig ? Line significance in σ; rms
noise of the moment-0 map of the line
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Note (1): Flag as follows:
l = Line luminosities and gas masses of lensed DSFG candidates.
The signatures of their lensed nature can be seen in
Berta+ (2021, J/A+A/646/A122); Stanley+ 2023ApJ...945...24S 2023ApJ...945...24S
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Global notes:
Note (G1): Flag as follows:
l = Line luminosities and gas masses of lensed DSFG candidates. Many of
these targets have known lensing factor µ>1 from
Borsato+ 2024MNRAS.528.6222B 2024MNRAS.528.6222B
Note (G2): Flag as follows:
* = CASA tclean mfs-mode-based net central frequency for a combined
continuum of individual IF1 and IF2 detections at two different
central frequencies.
Note (G3): For continuum non-detections (SNR<2), we provide the 3σc
upper-limits on the continuum flux densities (assuming an
unresolved emission within a beam), where σc is the rms noise
of a given continuum map.
Note (G4): Using an CO-H2 conversion factor, 4/αCO.
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Jul-2026