We show model light curves of superluminous supernova 2006gy on the assumption that the supernova is powered by the collision of supernova ejecta and its dense circumstellar medium .
The initial conditions are constructed based on the shock breakout condition , assuming that the circumstellar medium is dense enough to cause the shock breakout within it .
We perform a set of numerical light curve calculations by using a one-dimensional multigroup radiation hydrodynamics code STELLA .
We succeeded in reproducing the overall features of the early light curve of SN 2006gy with the circumstellar medium whose mass is about 15 ~ { } M _ { \odot } ( the average mass-loss rate \sim 0.1 ~ { } M _ { \odot } ~ { } \mathrm { yr ^ { -1 } } ) .
Thus , the progenitor of SN 2006gy is likely a very massive star .
The density profile of the circumstellar medium is not well constrained by the light curve modeling only , but our modeling disfavors the circumstellar medium formed by steady mass loss .
The ejecta mass is estimated to be comparable to or less than 15 ~ { } M _ { \odot } and the explosion energy is expected to be more than 4 \times 10 ^ { 51 } erg .
No ^ { 56 } Ni is required to explain the early light curve .
We find that the multidimensional effect , e.g. , the Rayleigh-Taylor instability , which is expected to take place in the cool dense shell between the supernova ejecta and the dense circumstellar medium , is important in understanding supernovae powered by the shock interaction .
We also show the evolution of the optical and near-infrared model light curves of high-redshift superluminous supernovae .
They can be potentially used to identify SN 2006gy-like superluminous supernovae in the future optical and near-infrared transient surveys .