Bibcode
Vazdekis, A.; Cenarro, A. J.; Gorgas, J.; Cardiel, N.; Peletier, R. F.
Bibliographical reference
Monthly Notice of the Royal Astronomical Society, Volume 340, Issue 4, pp. 1317-1345.
Advertised on:
4
2003
Citations
160
Refereed citations
145
Description
We present a new evolutionary stellar population synthesis model, which
predicts spectral energy distributions for single-age single-metallicity
stellar populations (SSPs) at resolution 1.5 Å (FWHM) in the
spectral region of the near-infrared CaII triplet feature. The main
ingredient of the model is a new extensive empirical stellar spectral
library that has been recently presented by Cenarro et al., which is
composed of more than 600 stars with an unprecedented coverage of the
stellar atmospheric parameters.
Two main products of interest for stellar population analysis are
presented. The first is a spectral library for SSPs with metallicities
-1.7 < [Fe/H] < +0.2, a large range of ages (0.1-18 Gyr) and
initial mass function (IMF) types. They are well suited to modelling
galaxy data, since the SSP spectra, with flux-calibrated response
curves, can be smoothed to the resolution of the observational data,
taking into account the internal velocity dispersion of the galaxy,
allowing the user to analyse the observed spectrum in its own system. We
also produce integrated absorption-line indices (namely CaT*, CaT and
PaT) for the same SSPs in the form of equivalent widths.
We find the following behaviour for the CaII triplet feature in old-aged
SSPs: (i) the strength of the CaT* index does not change much with time
for all metallicities for ages larger than ~3 Gyr; (ii) this index shows
a strong dependence on metallicity for values below [M/H]~-0.5 and (iii)
for larger metallicities this feature does not show a significant
dependence either on age or on the metallicity, being more sensitive to
changes in the slope of power-like IMF shapes.
The SSP spectra have been calibrated with measurements for globular
clusters by Armandroff & Zinn, which are well reproduced, probing
the validity of using the integrated CaII triplet feature for
determining the metallicities of these systems. Fitting the models to
two early-type galaxies of different luminosities (NGC 4478 and 4365),
we find that the CaII triplet measurements cannot be fitted unless a
very dwarf-dominated IMF is imposed, or if the Ca abundance is even
lower than the Fe abundance. More details can be found in work by
Cenarro et al.