Differences with van Dokkum & Franx (2001)


Equation (1) in the paper has been implemented as
P(tstop) ∝ exp((tstart-t)/τ)
to account for the fact that tstart can be >0

The time between cessation of star formation and morphological transformation to early-type galaxy is now a free parameter. In the paper this time was fixed at 0.1 x the age of the Universe, i.e., ~1.4 Gyr. It can now be set at any value; defaults are 0 for the "Default 1" model and 0.1 for the "Default 2" and "Default 3" models.

The paper only gives expressions for luminosity evolution in B and color evolution in U - B. Filters from U through K are offered here.

The default cosmology in the paper has Ωm=0.3, ΩΛ=0, although results for a Λ cosmology are also given. The calculator uses the "standard" Ωm=0.3, ΩΛ=0.7 cosmology. Note that the calculation is fully independent of the value of H0.

The values of κ (which describe the age-dependence of the luminosity in a given passband) are now determined from the Bruzual & Charlot (2003) models, using a Salpeter IMF and Solar metallicity. As described in the Help to the filters, other IMF's or metallicities can be accomodated as well.

The output is expanded with respect to the plots given in the paper: results are given out to z=3 rather than z=1, and the mean formation redshift of the stars in early-type galaxies at each epoch is now provided.

Note that more discussion on these topics is given in the Help links.