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Molecular gas, stars, and dust in sub-L⋆ star-forming galaxies at z ~ 2: Evidence for universal star formation and non-universal dust-to-gas ratio

Part of: IAU Issue 315 - From Interstellar Clouds...

Published online by Cambridge University Press:  12 September 2016

Miroslava Dessauges-Zavadsky ,
Michel Zamojski ,
Daniel Schaerer ,
Françoise Combes ,
Eiichi Egami ,
Panos Sklias ,
Mark A. Swinbank ,
Johan Richard  and
Tim Rawle
Miroslava Dessauges-Zavadsky
Affiliation:
Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Versoix, Switzerland
Michel Zamojski
Affiliation:
Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Versoix, Switzerland
Daniel Schaerer
Affiliation:
Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Versoix, Switzerland
Françoise Combes
Affiliation:
Observatoire de Paris, LERMA, 61 Avenue de l'Observatoire, 75014 Paris, France
Eiichi Egami
Affiliation:
Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, United States
Panos Sklias
Affiliation:
Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Versoix, Switzerland
Mark A. Swinbank
Affiliation:
Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE, United Kingdom
Johan Richard
Affiliation:
CRAL, Observatoire de Lyon, Université Lyon 1, 9 Avenue Ch. André, 69561 Saint Genis Laval Cedex, France
Tim Rawle
Affiliation:
ESAC, ESA, PO Box 78, Villanueva de la Canada, 28691 Madrid, Spain
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Abstract

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Current star-forming galaxies (SFGs) with CO measurements at z ~ 2 suffer from a bias toward high star formation rates (SFR) and high stellar masses (M*). It is yet essential to extend the CO measurements to the more numerous z ~ 2 SFGs with LIR < L⋆ = 4× 1011 L⊙ and M* < 2.5× 1010 M⊙. We have achieved CO, stars, and dust measurements in 8 such sub-L⋆ SFGs with the help of gravitational lensing. Combined with CO-detected galaxies from the literature, we find that the LIR, L′CO(1−0) data are best-fitted with a single relation that favours a universal star formation. This picture emerges because of the enlarged star formation efficiency spread of the current z>1 SFGs sample. We show that this spread is mostly triggered by the combination of redshift, specific SFR, and M*. Finally, we find evidence for a non-universal dust-to-gas ratio (DGR) with a clear trend for a lower DGR mean in z>1 SFGs by a factor of 2 with respect to local galaxies and high-redshift sub-mm galaxies at fixed about solar metallicity.

Keywords

Gravitational lensinggalaxies: evolutiongalaxies: high-redshift
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S315: From Interstellar Clouds to Star-Forming Galaxies: Universal Processes? , August 2015 , pp. 254 - 257
Copyright
Copyright © International Astronomical Union 2016 

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