One-dimensional delayed-detonation models of Type Ia supernovae: confrontation to observations at bolometric maximum

Abstract

The delayed-detonation explosion mechanism applied to a Chandrasekhar-mass white dwarf offers a very attractive model to explain the inferred characteristics of Type Ia supernovae (SNe Ia). The resulting ejecta are chemically stratified, have the same mass and roughly the same asymptotic kinetic energy, but exhibit a range in 56 Ni mass. We investigate the contemporaneous photometric and spectroscopic properties of a sequence of delayed-detonation models, characterized by 56 Ni masses between 0.18 and 0.81 M ⊙ . Starting at 1 d after explosion, we perform the full non-LTE, time-dependent radiative transfer with the code CMFGEN, with an accurate treatment of line blanketing, and compare our results to SNe Ia at bolometric maximum. Despite the 1D treatment, our approach delivers an excellent agreement to observations. We recover the range of SN Ia luminosities, colours, and spectral characteristics from the near-UV to 1 µm, for standard as well as low-luminosity 91bg-like SNe Ia. Our models predict an increase in rise time to peak with increasing 56 Ni mass, from ∼ 15 to ∼ 21 d, yield peak bolometric luminosities that match Arnett's rule to within 10 % and reproduce the much smaller scatter in near-IR magnitudes compared to the optical. We reproduce the morphology of individual spectral features, the stiff dependence of the R(Si) spectroscopic ratio on 56 Ni mass, and the onset of blanketing from Ti II/Sc II in low-luminosity SNe Ia with a 56 Ni mass 0.3 M ⊙ . We find that ionization effects, which often dominate over abundance variations, can produce high-velocity features in Ca II lines, even in 1D. Distinguishing between different SN Ia explosion mechanisms is a considerable challenge but the results presented here provide additional support to the viability of the delayed-detonation model.

A reddening-free method to estimate the56Ni mass of Type Ia supernovae

“…For the DDC models of Blondin et al (2013), α is within 10% of 1 for all but the least luminous model. A84, page 3 of 8 A&A 588, A84 (2016) Notes.…”

“…Recent 1D studies by Blondin et al (2013) compare a suite of Chandrasekhar mass (M Ch ) delayed detonation models with observations for SNe with a range of peak luminosities. They Fig.…”

Inferring supernova IIb/Ib/Ic ejecta properties from light curves and spectra: correlations from radiative-transfer models

“…Hence, knowledge of the distance and reddening to a given SN Ia gives the 56 Ni mass needed to match the peak luminosity. For SNe Ia, detailed radiative-transfer calculations suggest that this relation is fairly accurate (see, e.g., Blondin et al 2013), despite the various simplifications.…”

Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction

“…Here, we use the Arnett light-curve fit directly to estimate the 56 Ni mass and the amount of thermalized kinetic energy trapped and released, resulting in an effective α between 1.0 and 1.1 for LSQ12gdj. For the w = 0 Arnett formalism, α = 1 by construction, ignoring both opacity variation in the ejecta and/or less than complete gamma-ray deposition near maximum light (Blondin et al 2013). In Chandrasekhar-mass delayed detonation models (e.g.…”

“…If all of LSQ12gdj's luminosity is due to radioactive energy release, it could be (slightly) sub-Chandrasekhar-mass, a good candidate for a double detonation (Woosley & Weaver 1994;Fink et al 2010) of about 1.3 M , a conventional Chandrasekharmass near-pure detonation (Blondin et al 2013;Seitenzahl et al 2013), or a pulsating delayed detonation (Khokhlov et al 1993;Höflich & Khohklov 1996).…”