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Title: Type Ia supernovae from merging white dwarfs. II. Post-merger detonations

Merging carbon-oxygen (CO) white dwarfs are a promising progenitor system for Type Ia supernovae (SNe Ia), but the underlying physics and timing of the detonation are still debated. If an explosion occurs after the secondary star is fully disrupted, the exploding primary will expand into a dense CO medium that may still have a disk-like structure. This interaction will decelerate and distort the ejecta. Here we carry out multidimensional simulations of 'tamped' SN Ia models, using both particle and grid-based codes to study the merger and explosion dynamics and a radiative transfer code to calculate synthetic spectra and light curves. We find that post-merger explosions exhibit an hourglass-shaped asymmetry, leading to strong variations in the light curves with viewing angle. The two most important factors affecting the outcome are the scale height of the disk, which depends sensitively on the binary mass ratio, and the total {sup 56}Ni yield, which is governed by the central density of the remnant core. The synthetic broadband light curves rise and decline very slowly, and the spectra generally look peculiar, with weak features from intermediate mass elements but relatively strong carbon absorption. We also consider the effects of the viscous evolution of the remnantmore » and show that a longer time delay between merger and explosion probably leads to larger {sup 56}Ni yields and more symmetrical remnants. We discuss the relevance of this class of aspherical 'tamped' SN Ia for explaining the class of 'super-Chandrasekhar' SN Ia.« less
Authors:
;  [1] ; ;  [2] ;  [3]
  1. Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)
  2. Department of Physics and Department of Astronomy, University of California, Santa Cruz, CA (United States)
  3. Department of Physics and Department of Astronomy, University of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
22356636
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABUNDANCE; CARBON; CARBON MONOXIDE; DENSITY; EXPLOSIONS; HYDRODYNAMICS; MASS; NICKEL 56; NUCLEOSYNTHESIS; OXYGEN; RADIANT HEAT TRANSFER; SIMULATION; SPECTRA; SUPERNOVAE; TIME DELAY; VISIBLE RADIATION; WHITE DWARF STARS