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, V. 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. http://resolver.caltech.edu/CaltechAUTHORS:20150714-105208366
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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.
|Additional Information:||© 2015 ESO. Article published by EDP Sciences. Received 17 October 2014; Accepted 2 March 2015; Published online 19 June 2015. We are grateful to the referee for the careful reading of the manuscript and his/her useful suggestions. We thank Samuel Boissier, Véronique Buat, Andrea Cattaneo, Jared Gabor, Sylvain De La Torre and Mark Sargent for useful discussions. We thank Carlota Gruppioni for providing her data. We gratefully acknowledge the contributions of the entire COSMOS collaboration consisting of more than 100 scientists. The HST COSMOS program was supported through NASA grant HST-GO-09822. More information on the COSMOS survey is available at http://www.astro.caltech.edu/cosmos. This paper is based on observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. LMD acknowledges support from the Lyon Institute of Origins under grant ANR-10-LABX-66. A.K. acknowledges support by the Collaborative Research Council 956, sub-project A1, funded by the Deutsche Forschungsgemeinschaft (DFG).|
|Subject Keywords:||galaxies: evolution; galaxies: luminosity function, mass function; galaxies: stellar content; galaxies: star formation; galaxies: statistics; galaxies: formation|
|Official Citation:||O. Ilbert, S. Arnouts, E. Le Floc’h, H. Aussel, M. Bethermin, P. Capak, B.-C. Hsieh, M. Kajisawa, A. Karim, O. Le Fèvre, N. Lee, S. Lilly, H. J. McCracken, L. Michel-Dansac, T. Moutard, M. A. Renzini, M. Salvato, D. B. Sanders, N. Scoville, K. Sheth, J. D. Silverman, V. Smolčić, Y. Taniguchi and L. Tresse A&A 579 A2 (2015) DOI: http://dx.doi.org/10.1051/0004-6361/201425176|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 Jul 2015 00:04|
|Last Modified:||15 Jul 2015 00:04|
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