Chemical stratification of Type Iax Supernovae

Modeling of supernova (SN) spectra obtained at different epochs allows us to scan through the optically thin region of the atmosphere and provides the abundance distribution of the ejecta. If we fit not only a single spectrum, but a whole time series, we can map the chemical and physical properties of the ejecta. Constraining the chemical abundances with this technique called abundance tomography could allow a powerful tool to test the different explosion scenarios. However, the large number of free parameters and their degeneracy caused by the overlapping spectral lines challenge the analysis, which require carefully chosen spectral samples and fitting strategy. The members of the Type Iax SN subclass are peculiar thermonuclear explosions showing low peak absolute brightness and expansion velocities. Because of their narrow spectral lines and the extremely wide range of physical properties, SNe Iax offer excellent possibilities to perform abundance tomography and to test different explosion scenarios. In order to do that, we define a multi-layer atmosphere structure, where the fractions of the chemical elements are fitting parameters in each velocity shell. The fitting process was carried out using the 1D MC radiative transfer code TARDIS. Here we present the results from our abundance tomography analysis of several Type Iax SNe sampling well the diverse subclass. Based on the best-fit model maps, we discuss a possible correlation between the physical parameters and the chemical distribution. The fitting of the early spectra contradicts with the abundances in the outermost layers predicted by pure deflagration models, describing a promising explosion scenario for SNe Iax. Moreover, the peculiar nature of this subclass may allow us to extend the abundance tomography technique to later epochs and deeper layers. The mapping of the whole ejecta structure could also reveal the double-nature of the flux source observed in the late-time spectra of Type Iax SNe.