Abstract
We examine the growth and evolution of quenched galaxies in the mufasa
cosmological hydrodynamic simulations that include an evolving halo
mass-based quenching prescription, with galaxy colours computed
accounting for line-of-sight extinction to individual star particles.
mufasa reproduces the observed present-day red sequence reasonably well,
including its slope, amplitude and scatter. In mufasa, the red sequence
slope is driven entirely by the steep stellar mass-stellar metallicity
relation, which independently agrees with observations. High-mass
star-forming galaxies blend smoothly on to the red sequence, indicating
the lack of a well-defined green valley at M* ≳
1010.5 M⊙. The most massive galaxies quench
the earliest and then grow very little in mass via dry merging; they
attain their high masses at earlier epochs when cold inflows more
effectively penetrate hot haloes. To higher redshifts, the red sequence
becomes increasingly contaminated with massive dusty star-forming (SF)
galaxies; UVJ selection subtly but effectively separates these
populations. We then examine the evolution of the mass functions of
central and satellite galaxies split into passive and star-forming via
UVJ. Massive quenched systems show good agreement with observations out
to z ∼ 2, despite not including a rapid early quenching mode
associated with mergers. However, low-mass quenched galaxies are far too
numerous at z ≲ 1 in mufasa, indicating that mufasa strongly
overquenches satellites. A challenge for hydrodynamic simulations is to
devise a quenching model that produces enough early massive quenched
galaxies and keeps them quenched to z = 0, while not being so strong as
to overquench satellites; mufasa's current scheme fails at the latter.
Original language | English |
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Pages (from-to) | 1671-1687 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 471 |
Issue number | 2 |
DOIs | |
Publication status | Published - 21 Jul 2017 |
Keywords / Materials (for Non-textual outputs)
- galaxies: abundances
- galaxies: evolution
- galaxies: formation
- galaxies: luminosity function
- mass function