The VLA-COSMOS 3 GHz Large Project: Cosmic star formation history since z ~ 5

Novak, Mario and Smolčić, Vernesa and Delhaize, J. and Delvecchio, I. and Zamorani, G. and Baran, Nikola and Bondi, M. and Capak, P. and Carilli, C. L. and Ciliegi, P. and Civano, F. and Ilbert, O. and Karim, A. and Laigle, C. and Le Fèvre, O. and Marchesi, S. and McCracken, H. and Miettinen, O. and Salvato, M. and Sargent, M. and Schinnerer, E. and Tasca, L. (2017) The VLA-COSMOS 3 GHz Large Project: Cosmic star formation history since z ~ 5. Astronomy and Astrophysics, 602. Art. No. A5. ISSN 0004-6361

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We make use of the deep Karl G. Jansky Very Large Array (VLA) COSMOS radio observations at 3 GHz to infer radio luminosity functions of star-forming galaxies up to redshifts of z ~ 5 based on approximately 6000 detections with reliable optical counterparts. This is currently the largest radio-selected sample available out to z ~ 5 across an area of 2 square degrees with a sensitivity of rms ≈ 2.3 μJy beam^(-1). By fixing the faint and bright end shape of the radio luminosity function to the local values, we find a strong redshift trend that can be fitted with a pure luminosity evolution L_(1.4 GHz) ∝ (1 + z)^((3.16 ± 0.2)−(0.32 ± 0.07)z). We estimate star formation rates (SFRs) from our radio luminosities using an infrared (IR)-radio correlation that is redshift dependent. By integrating the parametric fits of the evolved luminosity function we calculate the cosmic SFR density (SFRD) history since z ~ 5. Our data suggest that the SFRD history peaks between 2 < z < 3 and that the ultraluminous infrared galaxies (100 M⊙ yr^(-1) < SFR < 1000 M⊙ yr^(-1)) contribute up to ~25% to the total SFRD in the same redshift range. Hyperluminous infrared galaxies (SFR > 1000 M⊙ yr^(-1)) contribute an additional ≲2% in the entire observed redshift range. We find evidence of a potential underestimation of SFRD based on ultraviolet (UV) rest-frame observations of Lyman break galaxies at high redshifts (z ≳ 4) on the order of 15–20%, owing to appreciable star formation in highly dust-obscured galaxies, which might remain undetected in such UV observations.

Item Type: Article
Keywords: galaxies, evolution – galaxies, star formation – cosmology, observations – radio continuum, galaxies
Date: 2017
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2017 ESO. Article published by EDP Sciences. Received 29 July 2016; Accepted 15 January 2017; Published online 13 June 2017. This research was funded by the European Unions Seventh Frame-work program under grant agreement 337595 (ERC Starting Grant, “CoSMass”). E.S. warmly acknowledges support from the National Radio Astronomy Observatory for visits to the Array Operations Center in Socorro, NM, in conjunction with this project. A.K. acknowledges support by the Collaborative Research Council 956, sub-project A1, funded by the Deutsche Forschungsgemeinschaft (DFG). M.B. and P.C. acknowledge support from the PRIN-INAF 2014.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 08 Nov 2017 10:40
Last Modified: 08 Nov 2017 10:40

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