Astrophys. J., 872, 91-91 (2019/February-2)
Quiescent galaxy size and spectroscopic evolution: combining HSC imaging and Hectospec spectroscopy.
DAMJANOV I., ZAHID H.J., GELLER M.J., UTSUMI Y., SOHN J. and SOUCHEREAU H.
Abstract (from CDS):
We explore the relationships between size, stellar mass, and average stellar population age (indicated by Dn4000 indices) for a sample of ∼11,000 intermediate-redshift galaxies from the SHELS spectroscopic survey (Geller et al. 2014) augmented by high-resolution Subaru Telescope Hyper Suprime-Cam imaging. In the redshift interval 0.1 < z < 0.6, star-forming galaxies are on average larger than their quiescent counterparts. The mass-complete sample of ∼3500 M*> 1010M☉ quiescent galaxies shows that the average size of a 1011M☉ quiescent galaxy increases by <=25% from z ∼ 0.6 to z ∼ 0.1. This growth rate is a function of stellar mass: the most massive (M*> 1011M☉) galaxies grow significantly more slowly in size than quiescent systems an order of magnitude less massive that grow by 70% in the 0.1 <= z <= 0.3 redshift interval. For M*< 1011M☉ galaxies, age and size are anticorrelated at fixed mass; more massive quiescent systems show no significant trend in size with average stellar population age. The evolution in absolute and fractional abundances of quiescent systems at intermediate redshift are also a function of galaxy stellar mass. The suite of evolutionary trends suggests that galaxies more massive than ∼1011M☉ have mostly assembled their mass by z ∼ 0.6. Quiescent galaxies with lower stellar masses show more complex evolution that is characterized by a combination of individual quiescent galaxy size growth (through mergers) and an increase in the size of newly quenched galaxies joining the population at later times (progenitor bias). The low-mass population (M*∼1010M☉) grows predominantly as a result of progenitor bias. For more massive (M*∼5×1010M☉) quiescent galaxies, (predominantly minor) mergers and progenitor bias make more comparable contributions to the size growth. At intermediate redshift, quiescent size growth is mass-dependent; the most massive (M*> 1011M☉) galaxies experience the least rapid increase in size from z ∼ 0.6 to z ∼ 0.1.
© 2019. The American Astronomical Society. All rights reserved.
galaxies: evolution - galaxies: fundamental parameters - galaxies: statistics - galaxies: stellar content - galaxies: structure
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<Available at CDS (J/ApJ/872/91): table1.dat>
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