Supernovae (SNe) are the most fascinating objects in astronomy and are<br />
intensely investigated. However, many mysteries such as nucleosynthesis and the<br />
origin of SNe Ia remain unsolved. Although the thermonuclear explosion of a<br />
single-degenerate white dwarf has been considered to be the origin of SNe Ia, a<br />
merger of two white dwarfs (double-degenerate scenario) has been frequently<br />
denoted to be more promising than a single-degenerate white dwarf. Recently the<br />
importance of observing the MeV gamma-ray band to conclusively determine the<br />
origin has been remarked. MeV gamma-rays are unique probes directly emitted<br />
from the exploding or merging region. It is evident that statistical analysis<br />
based on imaging spectroscopic observations of ~100 SNe Ia with MeV gamma-rays<br />
is necessary to obtain a definite answer. To achieve this, a telescope with a<br />
sensitivity that is 100 times that of COMPTEL is necessary. Proper imaging<br />
spectroscopy for the MeV gamma-ray band has been established by an<br />
electron-tracking Compton camera; hence, a concrete design of a MeV gamma-ray<br />
telescope has been proposed in our previous work. We have studied the details<br />
of the spectroscopic feature of SNe Ia based on the performance of a proposed<br />
telescope and found that statistical analysis can considerably suppress<br />
fluctuations of the individual properties of SNe and reveal their intrinsic<br />
differences in averaged light curves of SNe up to 60 Mpc. Our answer for the<br />
origin of SNe Ia extends to the case of single-degenerate scenario and<br />
double-degenerate coexistence scenario.