Título
QUALITATIVE INTERPRETATION OF GALAXY SPECTRA
Autor
ROBERTO GIOVANNI TERLEVICH AFONSO
Elena Kirilovsky Terlevich
Nivel de Acceso
Acceso Abierto
Materias
Resumen o descripción
We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra (Fig. 11). Rather than an alternative to existing automated tools, it is put forward as an instrument for quicklook analysis, and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is of general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7 (SDSS-DR7), thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to HII galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code starlight.We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a 1-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal rich or metal poor depending on whether they reside in passive galaxies or in star-forming galaxies.
Editor
The Astrophysical Journal
Fecha de publicación
17 de julio de 2012
Tipo de publicación
Artículo
Versión de la publicación
Versión aceptada
Recurso de información
Formato
application/pdf
Idioma
Inglés
Audiencia
Estudiantes
Investigadores
Público en general
Sugerencia de citación
Sánchez Almeida, J., et al., (2012), QUALITATIVE INTERPRETATION OF GALAXY SPECTRA, The Astrophysical Journal, Vol. 756(2):1-17
Repositorio Orígen
Repositorio Institucional del INAOE
Descargas
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