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

Villanueva, V., Ibar, E., Hughes, T.M., Lara-López, M.A., Dunne, Loretta, Eales, Stephen, Ivison, R.J., Aravena, M., Baes, M., Bourne, N., Cassata, P., Cooray, A., Dannerbauer, H., Davies, L.J.M., Driver, S.P., Dye, S., Furlanetto, C., Herrera-Camus, R., Maddox, Steve, Michałowski, M.J., Molina, J., Riechers, D., Sansom, A.E., Smith, Matthew, Rodighiero, G., Valiante, Elisabetta and Werf, P. van der 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. 10.1093/mnras/stx1338

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Abstract

We present an extragalactic survey using observations from the Atacama Large Millimeter/submillimeter Array (ALMA) to characterise 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 (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 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−1kpc−2)]=(1.26±0.02)×log[ΣMH2/(M⊙pc−2)]−(3.6±0.2) log⁡[ΣSFR/(M⊙yr−1kpc−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 long-standing mode of star-formation activity and a starburst, specially at LIR=1011−12L⊙ LIR=1011−12L⊙ .Combining our observations with data taken from the literature, we propose that star formation efficiencies can be parameterised by log[SFR/MH2]=0.19×(logLIR−11.45)−8.26−0.41×arctan[−4.84(logLIR−11.45)] log[SFR/MH2]=0.19×(logLIR−11.45)−8.26−0.41×arctan⁡[−4.84(log⁡LIR−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
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Additional Information: PDF uploaded in accordance with publisher's policies at http://www.sherpa.ac.uk/romeo/issn/0035-8711/ (accessed 14.7.17).
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 14 July 2017
Date of Acceptance: 27 May 2017
Last Modified: 15 Jan 2018 03:37
URI: http://orca.cf.ac.uk/id/eprint/102408

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