2022MNRAS.512.3566N -
Mon. Not. R. Astron. Soc., 512, 3566-3588 (2022/May-3)
Across the green valley with HST grisms: colour evolution, crossing time-scales, and the growth of the red sequence at z = 1.0-1.8.
NOIROT G., SAWICKI M., ABRAHAM R., BRADAC M., IYER K., MOUTARD T., PACIFICI C., RAVINDRANATH S. and WILLOTT C.J.
Abstract (from CDS):
We measure the colour evolution and quenching time-scales of z = 1.0-1.8 galaxies across the green valley. We derive rest-frame NUVrK colours and select blue-cloud, green-valley, and red-sequence galaxies from the spectral energy distribution modelling of CANDELS GOODS-South and UDS multiband photometry. Separately, we constrain the star-formation history (SFH) parameters (ages, τ) of these galaxies by fitting their deep archival HST grism spectroscopy. We derive the galaxy colour-age relation and show that only rapidly evolving galaxies with characteristic delayed-τ SFH time-scales of <0.5 Gyr reach the red sequence at these redshifts, after a period of accelerated colour evolution across the green valley. These results indicate that the stellar mass build-up of these galaxies stays minimal after leaving the blue cloud and entering the green valley (i.e. it may represent ≲5 per cent of the galaxies' final, quiescent masses). Visual inspection of age-sensitive features in the stacked spectra also supports the view that these galaxies follow a quenching sequence along the blue-cloud - green-valley - red-sequence track. For this rapidly evolving population, we measure a green-valley crossing time-scale of 0.99+0.42–0.25 Gyr and a crossing rate at the bottom of the green valley of 0.82+0.27–0.25 mag Gyr–1. Based on these time-scales, we estimate that the number density of massive (M* > 1010M☉) red-sequence galaxies doubles every Gyr at these redshifts, in remarkable agreement with the evolution of the quiescent galaxy stellar mass function. These results offer a new approach to measuring galaxy quenching over time and represent a pathfinder study for future JWST, Euclid, and Roman Space Telescope programs.
Abstract Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
galaxies: evolution - galaxies: general - galaxies: high-redshift
Simbad objects:
4
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