Modeling the LICK/IDS Spectral Feature Indices Using Synthetic Spectra

Tripicco, M.; Bell, R. A.

doi:10.1086/117744

Cited by 216 publications

(395 citation statements)

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“…The two flux-ratios show a large-scale variation of the continuum in the blue spectral region. These residuals include relevant features, which are related to carbon and some also to nitrogen, such as CNO at ∼ 3860Å, CaII H-K lines around ∼ 3950Å, CN at ∼ 4150Å, Ca at ∼ 4227Å, CH at ∼ 4300Å and C2 at ∼ 4670Å (see Tripicco & Bell 1995). Note that all these residuals are emphasised in the flux-ratio obtained for the high metallicity regime.…”

Section: Truly Scaled-solar and α-Enhanced Modelsmentioning

confidence: 97%

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Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models

Vazdekis

Coelho

Cassisi

et al. 2015

Monthly Notices of the Royal Astronomical Society

335

394

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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,

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Section: Truly Scaled-solar and α-Enhanced Modelsmentioning

confidence: 97%

“…Aiming at obtaining more quantitative determinations, models with varying abundance ratios were developed with the aid of theoretical stellar spectra (Tripicco & Bell 1995;Korn, Maraston & Thomas 2005). The responses obtained for the Lick indices to variations of the individual element abundances, i.e.…”

Section: Introductionmentioning

confidence: 99%

Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models

Vazdekis

Coelho

Cassisi

et al. 2015

Monthly Notices of the Royal Astronomical Society

335

394

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show abstract

“…The most recent models (e.g. Thomas et al 2003) take into account the non-solar abundances resulting from the different processes of metal enrichment by using the response functions of Tripicco & Bell (1995). Other families of models compute the SED, thus allowing the user to measure indices a posteriori if the spectral resolution is sufficient (e.g., Fioc & Rocca-Volmerange 1997;Leitherer et al 1999;Eisenstein et al 2003;Bruzual & Charlot 2003).…”

Section: Introductionmentioning

confidence: 99%

Evolutionary synthesis of galaxies at high spectral resolution with the code PEGASE-HR

Borgne

Rocca‐Volmerange

Prugniel

et al. 2004

A&A

367

389

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Abstract. We present PEGASE-HR, a new stellar population synthesis program generating high resolution spectra (R = 10 000) over the optical range λλ = 400-680 nm. It links the spectro-photometric model of galaxy evolution PEGASE.2 (Fioc & Rocca-Volmerange 1997) to an updated version of the ELODIE library of stellar spectra observed with the 193 cm telescope at the Observatoire de Haute-Provence (Prugniel & Soubiran 2001a). The ELODIE star set gives a fairly complete coverage of the Hertzprung-Russell (HR) diagram and makes it possible to synthesize populations in the range [Fe/H] = −2 to +0.4. This code is an exceptional tool for exploring signatures of metallicity, age, and kinematics. We focus on a detailed study of the sensitivity to age and metallicity of the high-resolution stellar absorption lines and of the classical metallic indices proposed until now to solve the age-metallicity degeneracy. Validity tests on several stellar lines are performed by comparing our predictions for Lick indices to the models of other groups. The comparison with the lower resolution library BaSeL (Lejeune et al. 1997) confirms the quality of the ELODIE library when used for single stellar populations (SSPs) from 10 7 to 2 × 10 10 yr. Predictions for the evolved populations of globular clusters and elliptical galaxies are given and compared to observational data. Two new highresolution indices are proposed around the Hγ line. They should prove useful in the analysis of spectra from the new generation of telescopes and spectrographs.

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“…1. Tripicco & Bell (1995) made a critical step forward and determined the sensitivity of Lick absorption-line indices to individual element abundance variations through model atmosphere calculations.…”

Section: Brief History Of Element Ratio Modellingmentioning

confidence: 99%

Element abundance ratios in stellar population modelling

Thomas

2014

Proc. IAU

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Abstract. I review the implementation of the effects from varying chemical element abundance ratios in stellar population modelling, focusing on α-and Fe-peak elements. A brief overview of the development of such models over the past 30 years is provided, starting with early work on the identification of relevant absorption features in the spectra of early-type galaxies in the 1980s leading to the most recent developments of the past years. Recent highlights include the adoption of new flux calibrated libraries, the inclusion of a wide range of chemical elements, the calculation of error estimates on the model, and the consideration of element variation effects on full spectra. The calibration of such models with globular clusters and some key results on the element ratios measured in early-type galaxies are presented.

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Modeling the LICK/IDS Spectral Feature Indices Using Synthetic Spectra

Cited by 216 publications

References 0 publications

Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models

Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models

Evolutionary synthesis of galaxies at high spectral resolution with the code PEGASE-HR

Element abundance ratios in stellar population modelling

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