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The stellar mass function of star-forming galaxies and the mass-dependent SFR function since z = 2.23 from HiZELS.

Sobral, D. and Best, P.N. and Smail, I. and Mobasher, B. and Stott, J. and Nisbet, D. (2014) 'The stellar mass function of star-forming galaxies and the mass-dependent SFR function since z = 2.23 from HiZELS.', Monthly notices of the Royal Astronomical Society., 437 (4). pp. 3516-3528.


We explore a large uniformly selected sample of Hα selected star-forming galaxies (SFGs) at z = 0.40, 0.84, 1.47, 2.23 to unveil the evolution of the star formation rate (SFR) function and the stellar mass function. We find strong evolution in the SFR function, with the typical SFR of SFGs declining exponentially in the last 11 Gyr as SFR*(T[Gyr]) = 104.23/T + 0.37 M⊙ yr−1, but with no evolution in the faint-end slope, α ≈ −1.6. The stellar mass function of SFGs, however, reveals little evolution: α ≈ −1.4, M* ∼ 1011.2 ± 0.2 M⊙ and just a slight increase of ∼2.3× in Φ* from z = 2.23 to z = 0.4. The stellar mass density within SFGs has been roughly constant since z = 2.23 at ∼107.65 ± 0.08 M⊙ Mpc−3, comprising ≈100 per cent of the stellar mass density in all galaxies at z = 2.23, and declining to ≈20 per cent by z = 0.40, driven by the rise of the passive population. We find that SFGs with ∼1010.0 ± 0.2 M⊙ contribute most to the SFR density (ρSFR) per d log10M, and that there is no significant evolution in the fractional contribution from SFGs of different masses to ρSFR or ρSFR(d log10M)−1 since z = 2.23. Instead, we show that the decline of SFR* and of ρSFR is primarily driven by an exponential decline in SFRs at all masses. Our results have important implications not only on how SFGs need to be quenched across cosmic time, but also on the driver(s) of the exponential decline in SFR* from ∼66 M⊙ yr−1 to 5 M⊙ yr−1 since z ∼ 2.23.

Item Type:Article
Keywords:Galaxies: evolution, Galaxies: fundamental parameters, Galaxies: high-redshift, Galaxies: luminosity function, Mass function, Galaxies: star formation, Cosmology: observations.
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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:20 June 2014
Date of first online publication:February 2014
Date first made open access:No date available

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