Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
arXiv:1504.08032 · doi:10.1093/mnras/stv151
Abstract
We present models that predict spectra of old- and intermediate-aged stellar populations at 2.51Å (FWHM) with varying [α/Fe] abundance. The models are based on the MILES library and on corrections from theoretical stellar spectra. The models employ recent [Mg/Fe] determinations for the MILES stars and BaSTI scaled-solar and α-enhanced isochrones. We compute models for a suite of IMF shapes and slopes, covering a wide age/metallicity range. Using BaSTI, we also compute "base models" matching The Galactic abundance pattern. We confirm that the α-enhanced models show a flux excess with respect to the scaled-solar models blue-ward 4500Å, which increases with age and metallicity. We also confirm that both [MgFe] and [MgFe]' indices are [α/Fe]-insensitive. We show that the sensitivity of the higher order Balmer lines to [α/Fe] resides in their pseudo-continua, with narrower index definitions yielding lower sensitivity. We confirm that the α-enhanced models yield bluer (redder) colours in the blue (red) spectral range. To match optical colours of massive galaxies we require both α-enhancement and a bottom-heavy IMF. The comparison of Globular Cluster line-strengths with our predictions match the [Mg/Fe] determinations from their individual stars. We obtain good fits to both full spectra and indices of galaxies with varying [α/Fe]. Using thousands of SDSS galaxy spectra we obtain a linear relation between a proxy for the abundance, [Z/Z], using solely scaled-solar models and the [Mg/Fe] derived with models with varying abundance ([Mg/Fe]=0.59[Z/Z]). Finally we provide a user-friendly, web-based facility, which allows composite populations with varying IMF and [α/Fe] ( http://miles.iac.es ).
Published in MNRAS,449,1177 (2015) http://adsabs.harvard.edu/abs/2015MNRAS.449.1177V . Models can be downloaded from http://miles.iac.es
References in corpus (23)
- The Dartmouth Stellar Evolution Database
- Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
- Population Synthesis in the Blue IV: Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
- Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
- Modeling the color evolution of luminous red galaxies - improvements with empirical stellar spectra
- Stellar populations of early-type galaxies in different environments II. Ages and metallicities
- Post-starburst galaxies: more than just an interesting curiosity
- The SAURON project - VI. Line strength maps of 48 elliptical and lenticular galaxies
- Spectral models for solar-scaled and alpha-enhanced stellar populations
- A Large Stellar Evolution Database for Population Synthesis Studies. III. Inclusion of the full Asymptotic Giant Branch phase and Web tools for stellar population analyses
- Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca
- Stellar populations of early-type galaxies in different environments I. Line-strength indices
- A large stellar evolution database for population synthesis studies. IV. Integrated properties and spectra
- Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. II. Test of Theoretical Stellar Isochrones
- The relation between stellar populations, structure and environment for dwarf elliptical galaxies from the MAGPOP-ITP
- An optimized H_βindex for disentangling stellar population ages
- Testing the Accuracy of Synthetic Stellar Libraries
- The Evolution of Oxygen and Magnesium in the Bulge and Disk of the Milky Way
- Stellar populations of Globular Clusters in the Elliptical galaxy NGC1407
- The Age, Metallicity and Alpha-Element Abundance of Galactic Globular Clusters from Single Stellar Population Models
- A new stellar library in the region of the CO index at 2.3 m. New index definition and empirical fitting functions
- Truncated Star Formation in Compact Groups of Galaxies: A Stellar Population Study
- Stellar populations of massive elliptical galaxies in very rich clusters