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Paper: A Spherical Chandrasekhar-Mass Delayed-Detonation Model for a Normal Type Ia Supernova
Volume: 493, 19th European Workshop on White Dwarfs
Page: 559
Authors: Blondin, S.; Dessart, L.; Hillier, D. J.
Abstract: The most widely-accepted model for Type Ia supernovae (SNe Ia) is the thermonuclear disruption of a White Dwarf (WD) star in a binary system, although there is ongoing discussion about the combustion mode, the progenitor mass, and the nature of the binary companion. Observational evidence for diversity in the SN Ia population seems to require multiple progenitor channels or explosion mechanisms. In the standard single-degenerate (SD) scenario, the WD grows in mass through accretion of H-rich or He-rich material from a non-degenerate donor (e.g., a main-sequence star, a subgiant, a He star, or a red giant). When the WD is sufficiently close to the Chandrasekhar limit (∼1.4 M☉), a subsonic deflagration front forms near the WD center which eventually transitions to a supersonic detonation (the so-called “delayed-detonation” model) and unbinds the star. The efficiency of the WD growth in mass remains uncertain, as repeated nova outbursts during the accretion process result in mass ejection from the WD surface. Moreover, the lack of observational signatures of the binary companion has cast some doubts on the SD scenario, and recent hydrodynamical simulations have put forward WD-WD mergers and collisions as viable alternatives. However, as shown here, the standard Chandrasekhar-mass delayed-detonation model remains adequate to explain many normal SNe Ia, in particular those displaying broad Si II 6355 Å lines. We present non-local-thermodynamic-equilibrium time-dependent radiative transfer simulations performed with CMFGEN of a spherically-symmetric delayed-detonation model from a Chandrasekhar-mass WD progenitor with 0.51 M☉ of 56Ni (Fig. 1 and Table 1), and confront our results to the observed light curves and spectra of the normal Type Ia SN 2002bo over the first 100 days of its evolution. With no fine tuning, the model reproduces well the bolometric (Fig. 2) and multi-band light curves, the secondary near-infrared maxima (Fig. 3), and the spectroscopic evolution (Fig. 4), illustrating the small impact of multi-dimensional processes for this event. Mergers or collisions of WD-WD systems should fare as well in reproducing the observational properties of normal SNe Ia to compete with the standard SD scenario.
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