Towards a library of synthetic galaxy spectra and preliminary results of classification and parametrization of unresolved galaxies for Gaia. II

Tsalmantza, P; Kontizas, M; Rocca-Volmerange, B; Bailer-Jones, CAL; Kontizas, E; Bellas-Velidis, I; Livanou, E; Korakitis, R; Dapergolas, A; Vallenari, A; Fioc, M

dc.contributor.author	Tsalmantza, P	en
dc.contributor.author	Kontizas, M	en
dc.contributor.author	Rocca-Volmerange, B	en
dc.contributor.author	Bailer-Jones, CAL	en
dc.contributor.author	Kontizas, E	en
dc.contributor.author	Bellas-Velidis, I	en
dc.contributor.author	Livanou, E	en
dc.contributor.author	Korakitis, R	en
dc.contributor.author	Dapergolas, A	en
dc.contributor.author	Vallenari, A	en
dc.contributor.author	Fioc, M	en
dc.date.accessioned	2014-03-01T01:32:12Z
dc.date.available	2014-03-01T01:32:12Z
dc.date.issued	2009	en
dc.identifier.issn	0004-6361	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20079
dc.subject	Galaxies: fundamental parameters	en
dc.subject	Techniques: photometric	en
dc.subject	Techniques: spectroscopic	en
dc.subject.classification	Astronomy & Astrophysics	en
dc.subject.other	Astrophysical parameters	en
dc.subject.other	Classification system	en
dc.subject.other	Emission lines	en
dc.subject.other	Gaia observations	en
dc.subject.other	Galaxies: fundamental parameters	en
dc.subject.other	Galaxy evolution	en
dc.subject.other	Low bias	en
dc.subject.other	Metallicities	en
dc.subject.other	Parameters estimated	en
dc.subject.other	Parametrizations	en
dc.subject.other	Random grids	en
dc.subject.other	Random values	en
dc.subject.other	Red shift	en
dc.subject.other	Regression model	en
dc.subject.other	Spectral class	en
dc.subject.other	Stellar spectra	en
dc.subject.other	SVM classifiers	en
dc.subject.other	Techniques: photometric	en
dc.subject.other	Techniques: spectroscopic	en
dc.subject.other	Time-scales	en
dc.subject.other	Wavelength ranges	en
dc.subject.other	Astrophysics	en
dc.subject.other	Emission spectroscopy	en
dc.subject.other	Parameter estimation	en
dc.subject.other	Photometry	en
dc.subject.other	Regression analysis	en
dc.subject.other	Support vector machines	en
dc.subject.other	Galaxies	en
dc.title	Towards a library of synthetic galaxy spectra and preliminary results of classification and parametrization of unresolved galaxies for Gaia. II	en
heal.type	journalArticle	en
heal.identifier.primary	10.1051/0004-6361/200912014	en
heal.identifier.secondary	http://dx.doi.org/10.1051/0004-6361/200912014	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	Aims. This paper is the second in a series, implementing a classification system for Gaia observations of unresolved galaxies. Our goals are to determine spectral classes and estimate intrinsic astrophysical parameters via synthetic templates. Here we describe (1) a new extended library of synthetic galaxy spectra; (2) its comparison with various observations; and (3) first results of classification and parametrization experiments using simulated Gaia spectrophotometry of this library.Methods. Using the PIGASE.2 code, based on galaxy evolution models that take account of metallicity evolution, extinction correction, and emission lines (with stellar spectra based on the BaSeL library), we improved our first library and extended it to cover the domain of most of the SDSS catalogue. Our classification and regression models were support vector machines (SVMs).Results. We produce an extended library of 28 885 synthetic galaxy spectra at zero redshift covering four general Hubble types of galaxies, over the wavelength range between 250 and 1050 nm at a sampling of 1 nm or less. The library is also produced for 4 random values of redshift in the range of 0-0.2. It is computed on a random grid of four key astrophysical parameters (infall timescale and 3 parameters defining the SFR) and, depending on the galaxy type, on two values of the age of the galaxy. The synthetic library was compared and found to be in good agreement with various observations. The first results from the SVM classifiers and parametrizers are promising, indicating that Hubble types can be reliably predicted and several parameters estimated with low bias and variance. © 2009 ESO.	en
heal.publisher	EDP SCIENCES S A	en
heal.journalName	Astronomy and Astrophysics	en
dc.identifier.doi	10.1051/0004-6361/200912014	en
dc.identifier.isi	ISI:000270180600034	en
dc.identifier.volume	504	en
dc.identifier.issue	3	en
dc.identifier.spage	1071	en
dc.identifier.epage	1084	en