Ejecta mass diagnostics of Type Ia supernovae

• Published in: Monthly notices of the Royal Astronomical Society 2018-03, Vol.474 (3), p.3187-3211
• Main Authors: Wilk, Kevin D, Hillier, D John, Dessart, Luc
• Format: Article
• Language: English
• Subjects: Astrophysics; Blanketing; Bolometers; Computer simulation; Detonation; Ejecta; Ejection; Explosions; Iron; Local thermodynamic equilibrium; Luminosity; Near infrared radiation; Photosphere; Physics; Radiative transfer; Sciences of the Universe; Supernovae; Time dependence
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx2816

Abstract We present one-dimensional non-local thermodynamic equilibrium time-dependent radiative transfer simulations (using cmfgen) of two sub-Chandrasekhar (sub-MCh), one MCh and one super-MCh Type Ia SN ejecta models. Three originate from MCh delayed detonation models, and the fourth is a sub-MCh detonation model. Ejecta masses are 1.02, 1.04, 1.40 and 1.70 M⊙, and all models have 0.62 M⊙ of 56Ni. Sub-MCh model light curves evolve faster, reaching bolometric maximum 2–3 d earlier and having 3–4 d shorter bolometric half-light widths. The models vary by ∼12 per cent at maximum bolometric luminosity and by 0.17 mag in Bmax. While ΔM15(B) increases with ejecta mass, it only varies by ∼5 per cent around 1 mag. Sub-MCh models are 0.25 mag bluer in B − R at Bmax. Optical spectra share many similarities, but lower mass models exhibit less UV line blanketing during the photospheric phase. At nebular times, significant near-infrared (NIR) spectroscopic differences are seen. In particular, emission lines of the Ca ii NIR triplet; [S iii] λλ9068,9530; [Ca ii] λλ7291,7324; [Ar iii] λλ7135,7751 and [Ni ii] 1.939 μm are stronger in higher mass models. The [Ni ii] 1.939 μm line is absent in the sub-MCh detonation model, and provides a valuable potential tool to distinguish sub-MCh explosions from MCh explosions. In general, the nebular phase models are too highly ionized. We attribute this to the neglect of clumping and/or the distribution of intermediate mass and iron group elements. The two sub-MCh models, while exploded by different mechanisms, can be distinguished in the J and H bands at late times (e.g. +200  d).