VALES I: the molecular gas content in star-forming dusty H-ATLAS galaxies up to z = 0.35

Villanueva, V. and Ibar, E. and Hughes, T.M. and Lara-Lopez, M.A. and Dunne, L. and Eales, S. and Ivison, R.J. and Aravena, M. and Baes, M. and Bourne, N. and Cassata, P. and Cooray, A. and Dannerbauer, H. and Davies, L.J.M. and Driver, S.P. and Dye, S. and Furlanetto, C. and Herrera-Camus, R. and Maddox, S.J. and Michałowski, M.J. and Molina, J. and Riechers, D. and Sansom, A.E. and Smith, M.W.L. and Rodighiero, G. and Valiante, E. and van der Werf, P. (2017) VALES I: the molecular gas content in star-forming dusty H-ATLAS galaxies up to z = 0.35. Monthly Notices of the Royal Astronomical Society, 470 (4). pp. 3775-3805. ISSN 1365-2966

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We present an extragalactic survey using observations from the Atacama Large Millimeter/submillimeter Array (ALMA) to characterize galaxy populations up to z = 0.35: the Valpara´ıso ALMA Line Emission Survey (VALES). We use ALMA Band-3 CO(1–0) observations to study the molecular gas content in a sample of 67 dusty normal star-forming galaxies selected from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). We have spectrally detected 49 galaxies at >5σ significance and 12 others are seen at low significance in stacked spectra. CO luminosities are in the range of (0.03–1.31) × 1010 K km s−1 pc2, equivalent to log(Mgas/M) = 8.9–10.9 assuming an αCO = 4.6 (K km s−1 pc2) −1, which perfectly complements the parameter space previously explored with local and high-z normal galaxies. We compute the optical to CO size ratio for 21 galaxies resolved by ALMA at ∼3.5 arcsec resolution (6.5 kpc), finding that the molecular gas is on average ∼ 0.6 times more compact than the stellar component. We obtain a global Schmidt–Kennicutt relation, given by log[[ΣSFR/(M yr−1 kpc−2)] = (1.26 ± 0.02) × log[ΣMH2 /(M pc−2)] − (3.6 ± 0.2). We find a significant fraction of galaxies lying at ‘intermediate efficiencies’ between a longstanding mode of star formation activity and a starburst, specially at LIR = 1011–12 L. Combining our observations with data taken from the literature, we propose that star formation efficiencies can be parametrized by log [SFR/MH2 ] = 0.19 × (log LIR − 11.45) − 8.26 − 0.41 × arctan[−4.84 (logLIR − 11.45)]. Within the redshift range we explore (z < 0.35), we identify a rapid increase of the gas content as a function of redshift.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: ISM: lines and bands, galaxies: high-redshift, galaxies: ISM, infrared: galaxies, submillimetre: galaxies
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
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Depositing User: Eprints, Support
Date Deposited: 25 Aug 2017 09:31
Last Modified: 18 Oct 2017 17:30

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