The peculiar Type Ia supernova iPTF14atg: Chandrasekhar-mass explosion or violent merger?

Understand

iPTF14atg, a subluminous peculiar Type Ia supernova (SN Ia) similar to SN 2002es, is the first SN Ia for which a strong UV flash was observed in the early-time light curves.

• This has been interpreted as evidence for a single-degenerate (SD) progenitor system where such a signal is expected from interactions between the SN ejecta and the non-degenerate companion star.
• Here, we compare synthetic observables of multi-dimensional state-of-the-art explosion models for different progenitor scenarios to the light curves and spectra of iPTF14atg.
• From our models, we have difficulties explaining the spectral evolution of iPTF14atg within the SD progenitor channel.