TY - JOUR
T1 - Galaxy formation in the Planck cosmology III
T2 - star-formation histories and post-processing magnitude reconstruction
AU - Shamshiri, Sorour
AU - Thomas, Peter A.
AU - Henriques, Bruno M
AU - Tojeiro, Rita
AU - Lemson, Gerard
AU - Oliver, Seb J.
AU - Wilkins, Stephen
PY - 2015/1/1
Y1 - 2015/1/1
N2 - We adapt the L-Galaxies semi-analytic model to follow the star-formation
histories (SFH) of galaxies -- by which we mean a record of the
formation time and metallicities of the stars that are present in each
galaxy at a given time. We use these to construct stellar spectra in
post-processing, which offers large efficiency savings and allows
user-defined spectral bands and dust models to be applied to data stored
in the Millennium data repository. We contrast model SFHs from the
Millennium Simulation with observed ones from the VESPA algorithm as
applied to the SDSS-7 catalogue. The overall agreement is good, with
both simulated and SDSS galaxies showing a steeper SFH with increased
stellar mass. The SFHs of blue and red galaxies, however, show poor
agreement between data and simulations, which may indicate that the
termination of star formation is too abrupt in the models. The mean
star-formation rate (SFR) of model galaxies is well-defined and is
accurately modelled by a double power law at all redshifts: SFR
proportional to 1/(x^{-1.39}+x^{1.33}), where x=(T-t)/3.0 Gyr, t is the
age of the stars and T is the loopback time to the onset of galaxy
formation; above a redshift of unity, this is well approximated by a
gamma function: SFR proportional to x^{1.5}e^{-x}, where x=(T-t)/2.0
Gyr. Individual galaxies, however, show a wide dispersion about this
mean. When split by mass, the SFR peaks earlier for high-mass galaxies
than for lower-mass ones, and we interpret this downsizing as a
mass-dependence in the evolution of the quenched fraction: the SFHs of
star-forming galaxies show only a weak mass dependence.
AB - We adapt the L-Galaxies semi-analytic model to follow the star-formation
histories (SFH) of galaxies -- by which we mean a record of the
formation time and metallicities of the stars that are present in each
galaxy at a given time. We use these to construct stellar spectra in
post-processing, which offers large efficiency savings and allows
user-defined spectral bands and dust models to be applied to data stored
in the Millennium data repository. We contrast model SFHs from the
Millennium Simulation with observed ones from the VESPA algorithm as
applied to the SDSS-7 catalogue. The overall agreement is good, with
both simulated and SDSS galaxies showing a steeper SFH with increased
stellar mass. The SFHs of blue and red galaxies, however, show poor
agreement between data and simulations, which may indicate that the
termination of star formation is too abrupt in the models. The mean
star-formation rate (SFR) of model galaxies is well-defined and is
accurately modelled by a double power law at all redshifts: SFR
proportional to 1/(x^{-1.39}+x^{1.33}), where x=(T-t)/3.0 Gyr, t is the
age of the stars and T is the loopback time to the onset of galaxy
formation; above a redshift of unity, this is well approximated by a
gamma function: SFR proportional to x^{1.5}e^{-x}, where x=(T-t)/2.0
Gyr. Individual galaxies, however, show a wide dispersion about this
mean. When split by mass, the SFR peaks earlier for high-mass galaxies
than for lower-mass ones, and we interpret this downsizing as a
mass-dependence in the evolution of the quenched fraction: the SFHs of
star-forming galaxies show only a weak mass dependence.
KW - Astrophysics - Astrophysics of Galaxies
KW - Astrophysics - Cosmology and Nongalactic Astrophysics
UR - http://adsabs.harvard.edu/abs/2015arXiv150105649S
M3 - Article
VL - 1501
JO - ArXiv e-prints
JF - ArXiv e-prints
M1 - 5649
ER -