TY - JOUR

T1 - The stellar mass function of star-forming galaxies and the mass-dependent SFR function since z = 2.23 from HiZELS

AU - Sobral, David

AU - Best, Philip N.

AU - Smail, Ian

AU - Mobasher, Bahram

AU - Stott, John

AU - Nisbet, David

PY - 2014/2/1

Y1 - 2014/2/1

N2 - We explore a large uniformly selected sample of Ha 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 ρSFR 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 ⊙; yr-1 since z ̃ 2.23.

AB - We explore a large uniformly selected sample of Ha 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 ρSFR 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 ⊙; yr-1 since z ̃ 2.23.

KW - Evolution - galaxies

KW - Fundamental parameters - galaxies

KW - Galaxies

KW - High-redshift - galaxies

KW - Luminosity function, mass function - galaxies

KW - Observations

KW - Star formation - cosmology

U2 - 10.1093/mnras/stt2159

DO - 10.1093/mnras/stt2159

M3 - Journal article

AN - SCOPUS:84891501473

VL - 437

SP - 3516

EP - 3528

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -