  We have developed a new galactic chemo-dynamical evolution code, called GCD+,
for studies of galaxy formation and evolution. This code is based on our
original three-dimensional tree N-body/smoothed particle hydrodynamics code
which includes self-gravity, hydrodynamics, radiative cooling, star formation,
supernova feedback, and metal enrichment. GCD+ includes a new Type II (SNe II)
and Ia (SNe Ia) supernovae model taking into account the lifetime of progenitor
stars, and chemical enrichment from intermediate mass stars. We apply GCD+ to
simulations of elliptical galaxy formation, and examine the colour-magnitude
relation (CMR), the Kormendy relation, and the [Mg/Fe]--magnitude relation of
simulation end-products. GCD+ is a useful and unique tool which enables us to
compare simulation results with the observational data directly and
quantitatively. Our simulation confirm the results of Kawata (2001) who uses a
simpler chemo-dynamical evolution code. We newly find that radiative cooling
becomes more efficient and thus the gas infall rate increases, with decreasing
mass of galaxies, which contributes to the slope of the CMR. In addition, the
sophisticated treatments of both SNe II and SNe Ia in GCD+ show that feedback
from SNe Ia plays a crucial role in the evolution of elliptical galaxies. We
conclude that the feedback effect of SNe Ia should not be ignored in studying
the evolution of elliptical galaxies.
