Abstract
Galaxies strongly self-regulate their growth via energetic feedback from
stars, supernovae, and black holes, but these processes are among the
least understood aspects of galaxy formation theory. We present an
analytic galaxy evolution model that directly constrains such feedback
processes from observed galaxy scaling relations. The equilibrium model,
which is broadly valid for star-forming central galaxies that dominate
cosmic star formation, is based on the ansatz that galaxies live in a
slowly evolving equilibrium between inflows, outflows, and star
formation. Using a Bayesian Monte Carlo Markov chain approach, we
constrain our model to match observed galaxy scaling relations between
stellar mass and halo mass, star formation rate, and metallicity from 0
<z <2. A good fit (χ2 ≈ 1.6) is achieved with
eight free parameters. We further show that constraining our model to
any two of the three data sets also produces a fit to the third that is
within reasonable systematic uncertainties. The resulting best-fitting
parameters that describe baryon cycling suggest galactic outflow
scalings intermediate between energy and momentum-driven winds, a weak
dependence of wind recycling time on mass, and a quenching mass scale
that evolves modestly upwards with redshift. This model further predicts
a stellar mass-star formation rate relation that is in good agreement
with observations to z ˜ 6. Our results suggest that this simple
analytic framework captures the basic physical processes required to
model the mean evolution of stars and metals in galaxies, despite not
incorporating many canonical ingredients of galaxy formation models such
as merging or disc formation.
Original language | English |
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Pages (from-to) | 1184-1200 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 452 |
Issue number | 2 |
DOIs | |
Publication status | Published - 14 Jul 2015 |
Keywords / Materials (for Non-textual outputs)
- galaxies: abundances- galaxies: evolution
- galaxies: formation