Autor(es)

Vazdekis, A. ; Coelho, P. ; Cassisi, S. ; Ricciardelli, E. ; Falcon-Barroso, J. ; Sanchez-Blazquez, P. ; La Barbera, F. ; Beasley, M. A. ; Pietrinferni, A.

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 449, n. 2, p. 38-pg., 2015-05-11.

Resumo

We present models that predict spectra of old-and intermediate-aged stellar populations at 2.51 angstrom (FWHM) with varying [alpha/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 alpha-enhanced isochrones. We compute models for a suite of initial mass function (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 alpha-enhanced models show a flux excess with respect to the scaled-solar models blueward similar to 4500 angstrom, which increases with age and metallicity. We also confirm that both [MgFe] and [MgFe]' indices are [alpha/Fe]-insensitive. We show that the sensitivity of the higher order Balmer lines to [alpha/Fe] resides in their pseudo-continua, with narrower index definitions yielding lower sensitivity. We confirm that the alpha-enhanced models yield bluer (redder) colours in the blue (red) spectral range. To match optical colours of massive galaxies, we require both alpha-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 [alpha/Fe]. Using thousands of SDSS galaxy spectra, we obtain a linear relation between a proxy for the abundance, [Z(Mg)/Z(Fe)](SS(BaSTI)), using solely scaled-solarmodels and the [Mg/Fe] derived with models with varying abundance ([Mg/Fe] = 0.59[Z(Mg)/Z(Fe)](SS(BaSTI))). Finally, we provide a user-friendly, web-based facility, which allows composite populations with varying IMF and [alpha/Fe]. (AU)

• Processo FAPESP: 08/58406-4 - The modelling of stellar populations and detailed abundance patterns
• Beneficiário: Paula Rodrigues Teixeira Coelho
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 09/09465-0 - O modelamento de populações estelares e padrões de abundância detalhados
• Beneficiário: Paula Rodrigues Teixeira Coelho
• Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores