Evolution of the dust emission of massive galaxies up to z = 4 and constraints on their dominant mode of star formation

Béthermin, Matthieu and Daddi, Emanuele and Magdis, Georgios and Lagos, Claudia and Sargent, Mark and Albrecht, Marcus and Aussel, Hervé and Bertoldi, Frank and Buat, Véronique and Galametz, Maud and Heinis, Sébastien and Ilbert, Olivier and Karim, Alexander and Koekemoer, Anton and Lacey, Cedric and Le Floc'h, Emeric and Navarrete, Felipe and Pannella, Maurilio and Schreiber, Corentin and Smolčić, Vernesa and Symeonidis, Myrto and Viero, Marco (2015) Evolution of the dust emission of massive galaxies up to z = 4 and constraints on their dominant mode of star formation. Astronomy and Astrophysics, 573. Art. No. 113. ISSN 0004-6361

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Abstract

We aim to measure the average dust and molecular gas content of massive star-forming galaxies (>3 × 10^(10)M_⊙) up to z = 4 in the COSMOS field to determine if the intense star formation observed at high redshift is induced by major mergers or is caused by large gas reservoirs. Firstly, we measured the evolution of the average spectral energy distributions as a function of redshift using a stacking analysis of Spitzer, Herschel, LABOCA, and AzTEC data for two samples of galaxies: normal star-forming objects and strong starbursts, as defined by their distance to the main sequence. We found that the mean intensity of the radiation field ⟨ U ⟩ heating the dust (strongly correlated with dust temperature) increases with increasing redshift up to z = 4 in main-sequence galaxies. We can reproduce this evolution with simple models that account for the decrease in the gas metallicity with redshift. No evolution of ⟨ U ⟩ with redshift is found in strong starbursts. We then deduced the evolution of the molecular gas fraction (defined here as M_(mol)/(M_(mol)+M_⋆)) with redshift and found a similar, steeply increasing trend for both samples. At z ~ 4, this fraction reaches ~60%. The average position of the main-sequence galaxies is on the locus of the local, normal star-forming disks in the integrated Schmidt-Kennicutt diagram (star formation rate versus mass of molecular gas), suggesting that the bulk of the star formation up to z = 4 is dominated by secular processes.

Item Type: Article
Keywords: galaxies: formation, galaxies: evolution, galaxies: high-redshift, galaxies: star formation, infrared: galaxies, submillimeter: galaxies
Date: 2015
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2015 ESO. Received: 19 September 2014. Accepted: 11 November 2014. Published online 07 January 2015.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 30 Apr 2015 17:06
Last Modified: 19 Apr 2016 10:42
URI: http://digre.pmf.unizg.hr/id/eprint/3926

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