Evolution of the specific star formation rate function at z < 1.4 Dissecting the mass-SFR plane in COSMOS and GOODS

Ilbert, O. and Arnouts, S. and Le Floc’h, E. and Aussel, H. and Bethermin, M. and Capak, P. and Hsieh, B.-C. and Kajisawa, M. and Karim, A. and Le Fèvre, O. and Lee, N. and Lilly, S. and McCracken, H. J. and Michel-Dansac, L. and Moutard, T. and Renzini, M. A. and Salvato, M. and Sanders, D. B. and Scoville, N. and Sheth, K. and Silverman, J. D. and Smolčić, Vernesa and Taniguchi, Y. and Tresse, L. (2015) Evolution of the specific star formation rate function at z < 1.4 Dissecting the mass-SFR plane in COSMOS and GOODS. Astronomy and Astrophysics, 579. Art. No. A2. ISSN 0004-6361

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The relation between the stellar mass (M⋆) and the star formation rate (SFR) characterizes how the instantaneous star formation is determined by the galaxy past star formation history and by the growth of the dark matter structures. We deconstruct the M⋆-SFR plane by measuring the specific SFR functions in several stellar mass bins from z = 0.2 out to z = 1.4 (specific SFR = SFR/M⋆, noted sSFR). Our analysis is primary based on a 24 μm selected catalogue combining the COSMOS and GOODS surveys. We estimate the SFR by combining mid- and far-infrared data for 20500 galaxies. The sSFR functions are derived in four stellar mass bins within the range 9.5 < log (M⋆ /M⊙) < 11.5. First, we demonstrate the importance of taking into account selection effects when studying the M⋆-SFR relation. Secondly, we find a mass-dependent evolution of the median sSFR with redshift varying as sSFR ∝ (1 + z)^b, with b increasing from b = 2.88^(±0.12) to b = 3.78^(± 0.60) between M⋆ = 10^(9.75) M⊙ and M⋆ = 10^(11.1) M⊙, respectively. At low masses, this evolution is consistent with the cosmological accretion rate and predictions from semi-analytical models (SAM). This agreement breaks down for more massive galaxies showing the need for a more comprehensive description of the star formation history in massive galaxies. Third, we obtain that the shape of the sSFR function is invariant with time at z< 1.4 but depends on the mass. We observe a broadening of the sSFR function ranging from 0.28 dex at M⋆ = 10^(9.75) M⊙ to 0.46 dex at M⋆ = 10^(11.1) M⊙. Such increase in the intrinsic scatter of the M⋆-SFR relation suggests an increasing diversity ofstar formation histories (SFHs) as the stellar mass increases. Finally, we find a gradual decline of the sSFR with stellar mass as log _(10)(sSFR) ∝ −0.17M⋆. We discuss the numerous physical processes, as gas exhaustion in hot gas halos or secular evolution, which can gradually reduce the sSFR and increase the SFH diversity.

Item Type: Article
Keywords: galaxies: evolution – galaxies: luminosity function, mass function – galaxies: stellar content – galaxies: star formation – galaxies: statistics – galaxies: formation
Date: 19 June 2015
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2015 ESO. Article published by EDP Sciences. Received 17 October 2014; Accepted 2 March 2015; Published online 19 June 2015.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 08 May 2016 20:13
Last Modified: 08 May 2016 20:13
URI: http://digre.pmf.unizg.hr/id/eprint/4807

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