Multidimensional simulations of the accretion-induced collapse of white dwarfs to neutron stars

L. Dessart, Adam S. Burrows, C. D. Ott, E. Livne, S. Y. Yoon, N. Langer

Research output: Contribution to journalArticle

168 Scopus citations

Abstract

We present 2.5-dimensional radiation-hydrodynamics simulations of the accretion-induced collapse (AIC) of white dwarfs, starting from two-dimensional rotational equilibrium configurations, thereby accounting consistently for the effects of rotation prior to and after core collapse. We focus our study on a 1.46 and a 1.92 M3 a model. Electron capture leads to the collapse to nuclear densities of these cores a few tens of milliseconds after the start of the simulations. The shock generated at bounce moves slowly, but steadily, outward. Within 50-100 ms, the stalled shock breaks out of the white dwarf along the poles. The blast is followed by a neutrino-driven wind that develops within the white dwarf, in a cone of ∼40° opening angle about the poles, with a mass loss rate of (5-8) × 10-3 M s -1. The ejecta have an entropy on the order of (20-50) kB baryon-1 and an electron fraction that is bimodal. By the end of the simulations, at ≳600 ms after bounce, the explosion energy has reached (3-4) × 1049 ergs and the mass has reached a few times 10 -3 M. We estimate the asymptotic explosion energies to be lower than 1050 ergs, significantly lower than those inferred for standard core collapse. The AIC of white dwarfs thus represents one instance where a neutrino mechanism leads undoubtedly to a successful, albeit weak, explosion. We document in detail the numerous effects of the fast rotation of the progenitors: the neutron stars are aspherical; the "ν μ" and ν̄e neutrino luminosities are reduced compared to the ve neutrino luminosity; the deleptonized region has a butterfly shape; the neutrino flux and electron fraction depends strongly upon latitude (a la von Zeipel); and a quasi-Keplerian 0.1-0.5 M accretion disk is formed.

Original languageEnglish (US)
Pages (from-to)1063-1084
Number of pages22
JournalAstrophysical Journal
Volume644
Issue number2 II
DOIs
StatePublished - Jun 10 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Hydrodynamics
  • Neutrinos
  • Stars: neutron
  • Stars: rotation
  • Supernovae: general
  • White dwarfs

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