Constraining Type Ia Supernovae with Models and Observations of Late-Time Light Curves

Type Ia supernovae (SNe Ia) are thermonuclear explosions of carbon-oxygen white dwarfs, and play a crucial role as standardizable candles for cosmology. The exact nature of the stellar progenitors and mechanisms of explosions of SNe Ia is still unknown. SNe Ia light curves are powered by the decay of radioactive Ni56 chain which is created during the explosion. However, observations of SNe Ia at late times, past 900 days past maximum light, indicate a flattening of the light curve, which are believed to be powered by 57Co abundances. In this talk, I will compare these observations against  computational nucleosynthetic yields of different types of models, and discuss the implications for the stellar progenitors of SNe Ia.