In the hyperz package we provided both observed SEDs and spectral
synthesis models, but the set of template SEDs can be changed by the user.
The mean spectra of local galaxies from Coleman, Wu & Weedman (1980,
hereafter CWW) are the most popular among the observed SEDs. In Figure
1 we show the four CWW template spectra, extended
in the UV and IR regions by means of Bruzual & Charlot spectra with
parameters (SFR and age) selected to match the observed spectra at .
These SEDs are contained in th files
In the panorama of synthetic spectra we chose the GISSEL98 (Galaxy Isochrone
Synthesis Spectral Evolution Library) spectral evolution library of Bruzual
& Charlot (1993), because of its easy implementation, good accuracy,
spectral coverage from UV to far-IR, and possibility of spectral evolution
to high redshift.
Figure:The four CWW mean observed
spectra of local galaxies. Because the original data of CWW extend only
we extrapolate the templates at ultraviolet and near-infrared wavelengths
using the spectral evolutionary models of Bruzual & Charlot (1993).
The stellar population synthesis models are based on stellar tracks
libraries; then, a spectral energy distribution is assigned to all stars
on the evolutionary tracks. Then, the Initial Mass Function (IMF) and the
Star Formation Rate (SFR) must be specified to follow the evolution of
the integrated spectrum.