
VALES I: the molecular gas content in star-forming dusty H-ATLAS galaxies up to z = 0.35
2017; Oxford University Press; Volume: 470; Issue: 4 Linguagem: Inglês
10.1093/mnras/stx1338
ISSN1365-2966
AutoresVicente Villanueva, E. Ibar, T. M. Hughes, M. A. Lara-López, L. Dunne, S. Eales, R. J. Ivison, M. Aravena, M. Baes, N. Bourne, P. Cassata, Asantha Cooray, H. Dannerbauer, L. J. M. Davies, Simon P. Driver, S. Dye, C. Furlanetto, R. Herrera-Camus, S. Maddox, M. J. Michałowski, Juan Molina, Dominik A. Riechers, A. E. Sansom, M. W. L. Smith, G. Rodighiero, E. Valiante, P. van der Werf,
Tópico(s)Astronomy and Astrophysical Research
ResumoWe present an extragalactic survey using observations from the Atacama Large Millimeter/submillimeter Array (ALMA) to characterize galaxy populations up to z = 0.35: the Valparaíso 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 |$\log ({{M}_{gas}/\mathrm{M}_{{\odot }}}) =8.9 \text{--} 10.9$| 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 |$\log [\Sigma _{\rm SFR}/({\rm M_{{\odot }} \,yr^{-1}\,kpc^{-2}})] =(1.26 \pm 0.02) \times \, \log [\Sigma _{{M}_{H2}}/({\rm M_{{\odot }}\,pc^{-2}})] - (3.6 \pm 0.2)$|. We find a significant fraction of galaxies lying at 'intermediate efficiencies' between a long-standing 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 |$\log \,[{{\rm SFR/}{M}_{H_2}}] = 0.19 \times \,{\rm (\log \,{L_{IR}} - 11.45)}-8.26- 0.41 \times \arctan [-4.84\,(\log {{L}_{IR}}-11.45) ]$|. Within the redshift range we explore (z < 0.35), we identify a rapid increase of the gas content as a function of redshift.
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