Abstract
Context. Analytical models of chemical evolution, including inflow and outflow of gas, are important tools for studying
how the metal content in galaxies evolves as a function of time.
Aims. We present new analytical solutions for the evolution of the gas mass, total mass, and metallicity of a galactic
system when a decaying exponential infall rate of gas and galactic winds are assumed. We apply our model to characterize
a sample of local star-forming and passive galaxies from the Sloan Digital Sky Survey data, with the aim of reproducing
their observed mass-metallicity relation.
Methods. We derived how the two populations of star-forming and passive galaxies differ in their particular distribution
of ages, formation timescales, infall masses, and mass loading factors.
Results. We find that the local passive galaxies are, on average, older and assembled on shorter typical timescales than
the local star-forming galaxies; on the other hand, the star-forming galaxies with higher masses generally show older
ages and longer typical formation timescales compared than star-forming galaxies with lower masses. The local starforming
galaxies experience stronger galactic winds than the passive galaxy population. Exploring the effect of assuming
different initial mass functions in our model, we show that to reproduce the observed mass-metallicity relation, stronger
winds are requested if the initial mass function is top-heavy. Finally, our analytical models predict the assumed sample
of local galaxies to lie on a tight surface in the 3D space defined by stellar metallicity, star formation rate, and stellar
mass, in agreement with the well-known fundamental relation from adopting gas-phase metallicity.
Conclusions. By using a new analytical model of chemical evolution, we characterize an ensemble of SDSS galaxies in
terms of their infall timescales, infall masses, and mass loading factors. Local passive galaxies are, on average, older and
assembled on shorter typical timescales than the local star-forming galaxies. Moreover, the local star-forming galaxies
show stronger galactic winds than the passive galaxy population. Finally, we find that the fundamental relation between
metallicity, mass, and star formation rate for these local galaxies is still valid when adopting the average galaxy stellar
metallicity.
how the metal content in galaxies evolves as a function of time.
Aims. We present new analytical solutions for the evolution of the gas mass, total mass, and metallicity of a galactic
system when a decaying exponential infall rate of gas and galactic winds are assumed. We apply our model to characterize
a sample of local star-forming and passive galaxies from the Sloan Digital Sky Survey data, with the aim of reproducing
their observed mass-metallicity relation.
Methods. We derived how the two populations of star-forming and passive galaxies differ in their particular distribution
of ages, formation timescales, infall masses, and mass loading factors.
Results. We find that the local passive galaxies are, on average, older and assembled on shorter typical timescales than
the local star-forming galaxies; on the other hand, the star-forming galaxies with higher masses generally show older
ages and longer typical formation timescales compared than star-forming galaxies with lower masses. The local starforming
galaxies experience stronger galactic winds than the passive galaxy population. Exploring the effect of assuming
different initial mass functions in our model, we show that to reproduce the observed mass-metallicity relation, stronger
winds are requested if the initial mass function is top-heavy. Finally, our analytical models predict the assumed sample
of local galaxies to lie on a tight surface in the 3D space defined by stellar metallicity, star formation rate, and stellar
mass, in agreement with the well-known fundamental relation from adopting gas-phase metallicity.
Conclusions. By using a new analytical model of chemical evolution, we characterize an ensemble of SDSS galaxies in
terms of their infall timescales, infall masses, and mass loading factors. Local passive galaxies are, on average, older and
assembled on shorter typical timescales than the local star-forming galaxies. Moreover, the local star-forming galaxies
show stronger galactic winds than the passive galaxy population. Finally, we find that the fundamental relation between
metallicity, mass, and star formation rate for these local galaxies is still valid when adopting the average galaxy stellar
metallicity.
| Original language | English |
|---|---|
| Number of pages | 11 |
| Journal | Astronomy & Astrophysics |
| Volume | 599 |
| Issue number | A6 |
| Early online date | 20 Feb 2017 |
| DOIs | |
| Publication status | Published - 1 Mar 2017 |
Keywords
- galaxies: abundances
- galaxies: evolution
- galaxies: ISM