Type Ia Supernovae From Merging White Dwarfs. I. Prompt Detonations

Journal Article · Tue Apr 01 00:00:00 EDT 2014 · The Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637x/785/2/105· OSTI ID:1565187

Moll, R. ^[1]; Raskin, C. ^[2]; Kasen, D. ^[3]; Woosley, S. E. ^[4]

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1. Univ. of California, Santa Cruz, CA (United States). Dept. of Astronomy and Astrophysics; Max Planck Inst. fuer Astrophysik, Garching (Germany)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Division
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Division ; Univ. of California, Berkeley, CA (United States). Dept. of Physics and Astronomy
4. Univ. of California, Santa Cruz, CA (United States). Dept. of Astronomy and Astrophysics

Merging white dwarfs are a possible progenitor of Type Ia supernovae (SNe Ia). Numerical models suggest that a detonation might be initiated before the stars have coalesced to form a single compact object. Here we study such prompt detonations by means of numerical simulations, modeling the disruption and nucleosynthesis of the stars until the ejecta reach the coasting phase, and generating synthetic light curves and spectra. Three models are considered with primary masses 0.96 $$M_⊙$$, 1.06 $$M_⊙$$, and 1.20 $$M_⊙$$. Of these, the 0.96 $$M_⊙$$ dwarf merging with a 0.81 $$M_⊙$$ companion, with an ⁵⁶Ni yield of 0.58 $$M_⊙$$, is the most promising candidate for reproducing common SNe Ia. The more massive mergers produce unusually luminous SNe Ia with peak luminosities approaching those attributed to "super-Chandrasekhar" mass SNe Ia. While the synthetic light curves and spectra of some of the models resemble observed SNe Ia, the significant asymmetry of the ejecta leads to large orientation effects. The peak bolometric luminosity varies by more than a factor of two with the viewing angle, and the velocities of the spectral absorption features are lower when observed from angles where the light curve is brightest. The largest orientation effects are seen in the ultraviolet, where the flux varies by more than an order of magnitude. The set of three models roughly obeys a width-luminosity relation, with the brighter light curves declining more slowly in the $$B$$ band. Spectral features due to unburned carbon from the secondary star are also seen in some cases.

• Research Organization: Univ. of California, Santa Cruz, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231; AC05-00OR22725; SC0008067; SC0010676
• OSTI ID: 1565187
• Journal Information: The Astrophysical Journal, Vol. 785, Issue 2; ISSN 0004-637X
• Publisher: Institute of Physics (IOP)
• Country of Publication: United States
• Language: English

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Astronomy & Astrophysics