J/A+A/538/A38 Synthetic galaxy spectra (Karampelas+, 2012)
Optimization of synthetic galaxy spectra. Application to ESA's Gaia mission.
Karampelas A., Kontizas M., Rocca-Volmerange B., Bellas-Velidis I.,
Kontizas E., Livanou E., Tsalmantza P., Dapergolas A.
<Astron. Astrophys. 538, A38 (2012)>
=2012A&A...538A..38K 2012A&A...538A..38K
ADC_Keywords: Galaxies, spectra ; Models
Keywords: methods: statistical - methods: data analysis -
galaxies: fundamental parameters
Abstract:
We present an optimized library of synthetic galaxy spectra that are
to be used for the Gaia satellite observations of unresolved galaxies.
These galaxy spectral templates are useful for the optimal performance
of the unresolved galaxy classifier (UGC) software. The UGC will
assign spectral classes to the observed unresolved galaxies by Gaia
(classification) and estimate some of their intrinsic astrophysical
parameters, which were used to create the synthetic library
(parametrization). We present the new optimized synthetic library of
galaxy spectra and the classification and parametrization results
using the Gaia-simulated version of this library.
To optimize our synthetic library, we applied the principal component
analysis (PCA) method to our synthetic spectra and studied the
influence of the star-formation rate parameters on the spectra, and
how these agree with some typical characteristics of the galaxy
spectral types. We used support vector machines (SVM) to classify and
parametrize the optimal simulated spectra.
The library of synthetic galaxy spectra was optimized. In this new set
of synthetic spectra, overlaps in spectral energy distributions and
colors are highly suppressed, while the results of UGC classification
are improved.
Description:
The data set includes the 12384 optimum synthetic galaxy spectra
described in the paper and the corresponding wavelength values. The
spectra were originally created with PEGASE.2 code
(http://www.iap.fr/pegase).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
wavelen.dat 13 1166 The wavelengths
spectra.fit 2880 40112 The synthetic galaxy spectra
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Byte-by-byte Description of file: wavelen.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1166] Sequential number of wavelength
7- 13 F7.2 nm lambda [249.5,1050.0] Wavelength (1)
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Note (1): In the spectra, wavelengths are identified with the sequential number.
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Acknowledgements:
Antonios Karampelas, ankaramp(at)phys.uoa.gr
(End) Antonios Karampelas [Univ. of Athens], Patricia Vannier [CDS] 16-Dec-2011