Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios

By D. Thomas, C. Maraston, J. Johansson. 2010

150 citations recorded by the source corpus.

We present new stellar population models of Lick absorption-line indices with variable element abundance ratios. The models are based on our new calibrations of absorption-line indices with stellar parameters derived from the MILES stellar library. The key novelty compared to our previous models is that they are now available at the higher spectral resolution of MILES (2.5 A full width at half-maximum) and flux calibrated, hence not tied anymore to the Lick/IDS system. This is essential for the interpretation of galaxy spectra where calibration stars are not available, such as large galaxy redshift surveys or other high-redshift observations. We note that the MILES resolution appears to be comparable to Sloan Digital Sky Survey (SDSS) resolution, so that our models can be applied to SDSS data without any corrections for instrumental spectral resolution. For the first time we provide random errors for the model predictions based on the uncertainties in the calibration functions and the underlying stellar parameter estimates. We show that random errors are small except at the edges of the parameter space (high/low metallicities and young ages ≲1 Gyr) where the stellar library is undersampled. We calibrate the base model for the parameters age, metallicity and α/Fe ratio with galactic globular cluster and galaxy gradient data. We discuss two model flavours with different input stellar evolutionary tracks from the Frascati and Padova groups. The new model release now includes abundance variations of the elements C, N, Mg, Na, Si, Ca, Ti, Cr and Fe. The individual elements that are best accessible with these models and the standard set of Lick absorption features are C, N, Mg, Ca, Ti and Fe. The model data are available at http://www.icg.port.ac.uk/∼thomasd.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6ce476de137d410005defb8ddddc2c8027fcf1de

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

SPIDER VIII - constraints on the stellar initial mass function of early-type galaxies from a variety of spectral features (2013, result): “Independent dynamical studies have arrived at similar conclusions (see, e.g., Thomas et al. 2011; Wegner et al. 2012; Cappellari et al. 2012a; Dutton, Mendel & Simard 2012; Tortora et al. 2013).”
Galaxy Masses: A Review (2013, background): “Progress can also be made by comparing dynamical and stellar population estimates to infer DM fractions and more generally the mass distribution in the central regions of galaxies (Gerhard et al. 2001; Cappellari et al. 2006; Napolitano et al. 2010; Thomas et al. 2011b; Wegner et al. 2012).”
Toward a Better Understanding of Cosmic Chronometers: A New Measurement of H(z) at z ∼ 0.7 (2021, methodology): “0.9, comparing an optimized set of spectral absorption features (HδA, CN1, CN2, Ca4227, G4300, HγA, HγF, Fe4383, Fe4531, C24668, hereafter baseline) with the Thomas et al. (2011) models.”
Systematic variation of the stellar initial mass function with velocity dispersion in early-type galaxies (2012, methodology): “We note that, according to Thomas et al. (2011a), both TiO1 and TiO2 are rather insensitive to non-solar abundance ratios.”
Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers (2012, background): “Even if some works [97, 98] have been developed to take into account also this effect in modeling stellar populations, the impact of considering the α-”
SDSS IV MaNGA – spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs (2016, methodology): “The stellar population models are the same as those predicting absorption-line indices including abundance-ratio effects, which are required to describe the absorption spectra of old galaxies and bulges (Thomas et al. 2004, 2011).”
THE STELLAR INITIAL MASS FUNCTION IN EARLY-TYPE GALAXIES FROM ABSORPTION LINE SPECTROSCOPY. II. RESULTS (2012, background): “Most SPS models that consider variable abundance patterns do not include the abundance effects on the isochrones (e.g., Thomas et al. 2003; Graves & Schiavon 2008; Thomas et al. 2011a), with the exception of the models of Coelho et al. (2007) and Lee et al. (2009).”
EARLY-TYPE GALAXY ARCHEOLOGY: AGES, ABUNDANCE RATIOS, AND EFFECTIVE TEMPERATURES FROM FULL-SPECTRUM FITTING (2013, methodology): “Based on the models of Thomas et al. (2011), J12 find [Mg/Fe]≈ 0.33 at the highest dispersions, corresponding to a remarkably short timescalof 0.2 Gyr.”
Stellar population models at high spectral resolution (2011, methodology): “The good agreement we find between solar-scaled models of Lick indices based on index-by-index fitting functions (Thomas et al. 2011) and those calculated on the full SED presented in this paper comes from removing these anomalous stars (see Section 5.5).”
The ATLAS3D Project – XXX. Star formation histories and stellar population scaling relations of early-type galaxies (2015, methodology): “For comparison, we also show equivalent cubic fits derived from the ‘TMJ’ models of Thomas et al. (2011) using the stellar evolutionary tracks of Cassisi et al. (1997, ‘TMJ+Cassisi’) and the Padova group (Girardi et al. 2000, ‘TMJ+Padova’).”