Article

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

Markus KromerThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenC. FremlingThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenRüdiger PakmorHeidelberger Institut fr Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, GermanyS. TaubenbergerEuropean Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Mnchen, GermanyR. AmanullahThe Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenS. B. CenkoAstrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771, USAClaes FranssonThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenA. GoobarThe Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenG. LeloudasDark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-2100 Copenhagen, DenmarkF. TaddiaThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenF. K. RöpkeHeidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, GermanyI. R. SeitenzahlARC Centre of Excellence for All-Sky Astrophysics (CAASTRO)Stuart SimARC Centre of Excellence for All-Sky Astrophysics (CAASTRO)J. SollermanThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden

2016en

ABI

Abstract

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 multidimensional 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. In contrast, we find that a violent merger of two carbon-oxygen white dwarfs with 0.9 and 0.76 M , respectively, provides an excellent match to the spectral evolution of iPTF14atg from 10 d before to several weeks after maximum light. Our merger model does not naturally explain the initial UV flash of iPTF14atg. We discuss several possibilities like interactions of the SN ejecta with the circumstellar medium and surface radioactivity from an He-ignited merger that may be able to account for the early UV emission in violent merger models.

Identifiers

DOI: 10.1093/mnras/stw962

Citations and references

Cited by 20 references

Metrics — AkademScholar