Template SEDs

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 $z=0$. These SEDs are contained in th files
./ZPHOT/templates/CWW_E_ext.sed
./ZPHOT/templates/CWW_Sbc_ext.sed
./ZPHOT/templates/CWW_Scd_ext.sed
./ZPHOT/templates/CWW_Im_ext.sed

Figure:The four CWW mean observed spectra of local galaxies. Because the original data of CWW extend only from $1400$ to $10000$Å, we extrapolate the templates at ultraviolet and near-infrared wavelengths using the spectral evolutionary models of Bruzual & Charlot (1993).

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.

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.
 

2000-12-10