  We numerically investigate light curves (LCs) of shocked circumstellar shells
which are suggested to reproduce the observed LC of superluminous SN 2006gy
analytically. In the previous analytical model, the effects of the
recombination and the bolometric correction on LCs are not taken into account.
To see the effects, we perform numerical radiation hydrodynamic calculations of
shocked shells by using STELLA, which can numerically treat multigroup
radiation transfer with realistic opacities. We show that the effects of the
recombination and the bolometric correction are significant and the analytical
model should be compare to the bolometric LC instead of a single band LC. We
find that shocked circumstellar shells have a rapid LC decline initially
because of the adiabatic expansion rather than the luminosity increase and the
shocked shells fail to explain the LC properties of SN 2006gy. However, our
synthetic LCs are qualitatively similar to those of superluminous SN 2003ma and
SN 1988Z and they may be related to shocked circumstellar shells.
