TY - JOUR

T1 - Forensic reconstruction of galaxy colour evolution and population characterization

AU - Bravo, Matias

AU - Robotham, Aaron S. G.

AU - Lagos, Claudia del P.

AU - Davies, Luke J. M.

AU - Bellstedt, Sabine

AU - Thorne, Jessica E.

PY - 2022/3/8

Y1 - 2022/3/8

N2 - Mapping the evolution of galaxy colours, from blue star forming to red passive systems, is fundamental to understand the processes involved in galaxy evolution. To this end, we reconstruct the colour evolution of low-redshift galaxies, combining stellar templates with star formation and metallicity histories of galaxies from the Galaxy And Mass Assembly survey and shark semi-analytical model. We use these colour histories to robustly characterize the evolution of red and blue galaxy populations over cosmic time. Using a Gaussian Mixture Model to characterize the colour distribution at any given epoch and stellar mass, we find both observations and simulations strongly favour a model with only two populations (blue and red), with no evidence for a third 'green' population. We map the evolution of mean, weight, and scatter of the blue and red populations as a function of both stellar mass and lookback time. Using our simulated galaxy catalogue as a testbed, we find that we can accurately recover galaxies colour histories up to a lookback time of similar to 6 Gyr. We find that both populations show little change in the mean colour for low-mass galaxies, while the colours at the massive end become significantly redder with time. The stellar mass above which the galaxy population is predominantly red decreases by 0.3 dex in the last 5 Gyrs. We find a good agreement between observations and simulations, with the largest tension being that massive galaxies from shark are too blue (a known issue with many galaxy evolution models).

AB - Mapping the evolution of galaxy colours, from blue star forming to red passive systems, is fundamental to understand the processes involved in galaxy evolution. To this end, we reconstruct the colour evolution of low-redshift galaxies, combining stellar templates with star formation and metallicity histories of galaxies from the Galaxy And Mass Assembly survey and shark semi-analytical model. We use these colour histories to robustly characterize the evolution of red and blue galaxy populations over cosmic time. Using a Gaussian Mixture Model to characterize the colour distribution at any given epoch and stellar mass, we find both observations and simulations strongly favour a model with only two populations (blue and red), with no evidence for a third 'green' population. We map the evolution of mean, weight, and scatter of the blue and red populations as a function of both stellar mass and lookback time. Using our simulated galaxy catalogue as a testbed, we find that we can accurately recover galaxies colour histories up to a lookback time of similar to 6 Gyr. We find that both populations show little change in the mean colour for low-mass galaxies, while the colours at the massive end become significantly redder with time. The stellar mass above which the galaxy population is predominantly red decreases by 0.3 dex in the last 5 Gyrs. We find a good agreement between observations and simulations, with the largest tension being that massive galaxies from shark are too blue (a known issue with many galaxy evolution models).

KW - techniques: photometric

KW - galaxies: evolution

KW - MASS ASSEMBLY GAMA

KW - SPECTRAL-ENERGY-DISTRIBUTIONS

KW - STAR-FORMATION HISTORIES

KW - SUPERMASSIVE BLACK-HOLES

KW - ACTIVE GALACTIC NUCLEI

KW - QUENCHING TIME-SCALES

KW - STELLAR MASS

KW - LUMINOSITY FUNCTIONS

KW - SEMIANALYTIC MODEL

KW - MAGNITUDE RELATION

U2 - 10.1093/mnras/stac321

DO - 10.1093/mnras/stac321

M3 - Journal article

VL - 511

SP - 5405

EP - 5427

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 4

ER -