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

Autor(es)

Vazdekis, A. ^{[1, 2]} ; Coelho, P. ^[3] ; Cassisi, S. ^[4] ; Ricciardelli, E. ^[5] ; Falcon-Barroso, J. ^{[1, 2]} ; Sanchez-Blazquez, P. ^[6] ; La Barbera, F. ^[7] ; Beasley, M. A. ^{[1, 2]} ; Pietrinferni, A. ^[4]

Afiliação do(s) autor(es)

^[1] IAC, E-38200 San Cristobal la Laguna, Tenerife - Spain

^[2] Univ La Laguna, Dept Astrofis, E-38205 Tenerife - Spain

^[3] Univ Fed Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil

^[4] INAF Osservatorio Astron Collurania, I-64100 Teramo - Italy

^[5] Univ Valencia, Dept Astron & Astrofis, E-46100 Valencia - Spain

^[6] Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid - Spain

^[7] INAF Osservatorio Astron Capodimonte, I-80131 Naples - Italy

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 449, n. 2, p. 1177-1214, MAY 11 2015.
• Citações Web of Science: 93

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: 09/09465-0 - O modelamento de populações estelares e padrões de abundância detalhados
• Beneficiário: Paula Rodrigues Teixeira Coelho
• Linha de fomento: Bolsas no Brasil - Apoio a Jovens Pesquisadores
• Processo FAPESP: 08/58406-4 - A modelagem de populações estelares e padrões de abundância detalhados
• Beneficiário: Paula Rodrigues Teixeira Coelho
• Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores