The model assumes that all progenitors of early-type galaxies started forming stars at a time tstart, ended forming stars at a time tstop, and that some time after the end of star formation they are morphologically classified as early-type. Three possible star formation histories are shown here:
The time tstart
is the same for all galaxies in the simulation,
but the time tstop
is different for each galaxy. In the simulation, the values of
tstop are drawn from an exponential probability
distribution with characteristic scale τ:
After entering a value for τ, click "Apply" to calculate the corresponding fraction of today's early-type galaxies that have formed by z=1.