Examinando por Autor "Vazdekis, A."

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Acceso Abierto
A few StePS forward in unveiling the complexity of galaxy evolution: light-weighted stellar ages of intermediate-redshift galaxies with WEAVE
(EDP Sciences, 2019-11-21) Costantin, L.; Lovino, A.; Zibetti, S.; Longhetti, M.; Gallazzi, A.; Mercurio, A.; Lonoce, I.; Balcells, M.; Bolzonella, M.; Busarello, G.; Dalton, G.; Ferré Mateu, A.; García Benito, R.; Gargiulo, A.; Haines, C.; Jin, S.; La Barbera, F.; McGee, S.; Merluzzi, P.; Morelli, L.; Murphy, D. N. A.; Peralta de Arriba, L.; Pizzella, A.; Poggianti, B. M.; Pozzetti, L.; Sánchez Blázquez, P.; Talia, M.; Tortora, C.; Trager, S. C.; Vazdekis, A.; Vergani, D.; Vulcani, B.; Istituto Nazionale di Astrofisica (INAF); Comunidad de Madrid; Fundación Caixa; Agencia Estatal de Investigación (AEI); Vulcani, B. [0000-0003-0980-1499]; De Arribas, L. P. [0000-0002-3084-084X]; Zibetti, S. [0000-0003-1734-8356]; Talia, M. [0000-0003-4352-2063]; Tortora, C. [0000-0001-7958-6531]; Pizzella, A. [0000-0001-9585-417X]; Ferré Mateu, A. [0000-0002-6411-220X]; McGee, S. [0000-0003-3255-3139]; Gargiulo, A. [0000-0002-3351-1216]; Longhetti, M. [0000-0002-6142-4822]; Gallazzi, A. [0000-0002-9656-1800]; Vergani, D. [0000-0003-0898-2216]; Haines, C. [0000-0002-8814-8960]; Costantin, L. [0000-0001-6820-0015]; Pozzetti, L. [0000-0001-7085-0412]; Dalton, G. [0000-0002-3031-2588]; Iovino, A. [0000-0001-6958-0304]; Sánchez Blázquez, P. [0000-0003-0651-0098]; Merluzzi, P. [0000-0003-3966-2397]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The upcoming new generation of optical spectrographs on four-meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide invaluable information for reconstructing the history of star formation in individual galaxies up to redshifts of about 0.7. Aims. We aim at defining simple but robust and meaningful physical parameters that can be used to trace the coexistence of widely diverse stellar components: younger stellar populations superimposed on the bulk of older ones. Methods. We produced spectra of galaxies closely mimicking data from the forthcoming Stellar Populations at intermediate redshifts Survey (StePS), a survey that uses the WEAVE spectrograph on the William Herschel Telescope. First, we assessed our ability to reliably measure both ultraviolet and optical spectral indices in galaxies of different spectral types for typically expected signal-to-noise ratios. We then analyzed such mock spectra with a Bayesian approach, deriving the probability density function of r- and u-band light-weighted ages as well as of their difference. Results. We find that the ultraviolet indices significantly narrow the uncertainties in estimating the r- and u-band light-weighted ages and their difference in individual galaxies. These diagnostics, robustly retrievable for large galaxy samples even when observed at moderate signal-to-noise ratios, allow us to identify secondary episodes of star formation up to an age of ∼0.1 Gyr for stellar populations older than ∼1.5 Gyr, pushing up to an age of ∼1 Gyr for stellar populations older than ∼5 Gyr. Conclusions. The difference between r-band and u-band light-weighted ages is shown to be a powerful diagnostic to characterize and constrain extended star-formation histories and the presence of young stellar populations on top of older ones. This parameter can be used to explore the interplay between different galaxy star-formation histories and physical parameters such as galaxy mass, size, morphology, and environment.
Restringido
Surface brightness fluctuation spectra to constrain stellar population properties.
(Oxford Academics: Oxford University Press, 2020-03-04) Vazdekis, A.; Cerviño, M.; Montes, M.; Martín Navarro, I.; Beasley, M. A.; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Beasley, M. A. [0000-0002-4694-2250]; Vazdekis, A. [0000-0002-6259-8293]; Montes, M. [0000-0001-7847-0393]; Cervino, M. [0000-0001-8009-231X]; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC), SEV-2015-0548; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a new set of surface brightness fluctuation (SBF) spectra computed with the E-MILES stellar population synthesis models. The model SBF spectra cover the range λλ1680–50 000 at moderately high resolution, all based on extensive empirical stellar libraries. The models span the metallicity range −2.3≤[M/H]≤+0.26 for a suite of intial mass function types with varying slopes. These predictions can complement and aid fluctuation magnitude studies, permitting a first-order approximation by applying filter responses to the SBF spectra to obtain spectroscopic SBF magnitudes. We provide a recipe for obtaining the latter and discuss their uncertainties and limitations. We compare our spectroscopic SBF magnitudes to photometric data of a sample of early-type galaxies. We also show that the SBF spectra can be very useful for constraining relevant stellar population parameters. We find small (<5 per cent) mass fractions of extremely metal-poor components (⁠[M/H]<−1⁠) on the top of the dominant, old, and metal-rich stellar population. These results put stringent constraints on the early stages of galaxy formation in massive elliptical galaxies. This is remarkable given the high degree of degeneracy of the standard spectral analysis to such metal-poor stellar populations in the visible and in the near-infrared. The new SBF models show great potential for exploiting ongoing surveys, particularly those based on narrow-band filters.