Model atmospheres for type Ia supernovae: Basic steps towards realistic synthetic spectra

Type Ia supernovae are an important tool for studying the expansion history of the universe. Advancing our yet incomplete understanding of the explosion scenario requires detailed and realistic numerical models in order to interpret and analyze the growing amount of observational data. Here we present first results of our new NLTE model calculations for the expanding atmospheres of type Ia supernovae that employ a detailed and consistent treatment of all important NLTE effects as well as line blocking and blanketing. The comparison of the synthetic spectra resulting from these models with observed data shows that the employed methods represent an important step towards a more realistic description of the atmospheres of supernovae Ia.