skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: STABILITY OF A SPHERICAL ACCRETION SHOCK WITH NUCLEAR DISSOCIATION

Abstract

We examine the stability of a standing shock wave within a spherical accretion flow onto a gravitating star, in the context of core-collapse supernova explosions. Our focus is on the effect of nuclear dissociation below the shock on the linear growth, and nonlinear saturation, of nonradial oscillations of the shocked fluid. We combine two-dimensional, time-dependent hydrodynamic simulations using FLASH2.5 with a solution to the linear eigenvalue problem, and demonstrate the consistency of the two approaches. Previous studies of this 'standing accretion shock instability' (SASI) have focused either on zero-energy accretion flows without nuclear dissociation, or made use of a detailed finite-temperature nuclear equation of state and included strong neutrino heating. Our main goal in this and subsequent papers is to introduce equations of state of increasing complexity, in order to isolate the various competing effects. In this work, we employ an ideal gas equation of state with a constant rate of nuclear dissociation below the shock, and do not include neutrino heating. We find that a negative Bernoulli parameter below the shock significantly lowers the real frequency, growth rate, and saturation amplitude of the SASI. A decrease in the adiabatic index has similar effects. The nonlinear development of the instabilitymore » is characterized by an expansion of the shock driven by turbulent kinetic energy at nearly constant internal energy. Our results also provide further insight into the instability mechanism: the rate of growth of a particular mode is fastest when the radial advection time from the shock to the accretor overlaps with the period of a standing lateral sound wave. The fastest-growing mode can therefore be modified by nuclear dissociation.« less

Authors:
 [1];  [2]
  1. Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada)
  2. Canadian Institute for Theoretical Astrophysics, Toronto, Ontario M5S 3H8 (Canada)
Publication Date:
OSTI Identifier:
21307916
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 697; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/697/2/1827; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABUNDANCE; ADVECTION; COSMIC NEUTRINOS; EIGENVALUES; EQUATIONS OF STATE; EXPLOSIONS; HYDRODYNAMICS; KINETIC ENERGY; NONLINEAR PROBLEMS; NUCLEAR REACTIONS; NUCLEAR TEMPERATURE; NUCLEOSYNTHESIS; SHOCK WAVES; SOUND WAVES; SUPERNOVAE; TIME DEPENDENCE

Citation Formats

Fernandez, Rodrigo, and Thompson, Christopher. STABILITY OF A SPHERICAL ACCRETION SHOCK WITH NUCLEAR DISSOCIATION. United States: N. p., 2009. Web. doi:10.1088/0004-637X/697/2/1827; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Fernandez, Rodrigo, & Thompson, Christopher. STABILITY OF A SPHERICAL ACCRETION SHOCK WITH NUCLEAR DISSOCIATION. United States. https://doi.org/10.1088/0004-637X/697/2/1827; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)
Fernandez, Rodrigo, and Thompson, Christopher. Mon . "STABILITY OF A SPHERICAL ACCRETION SHOCK WITH NUCLEAR DISSOCIATION". United States. https://doi.org/10.1088/0004-637X/697/2/1827; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21307916,
title = {STABILITY OF A SPHERICAL ACCRETION SHOCK WITH NUCLEAR DISSOCIATION},
author = {Fernandez, Rodrigo and Thompson, Christopher},
abstractNote = {We examine the stability of a standing shock wave within a spherical accretion flow onto a gravitating star, in the context of core-collapse supernova explosions. Our focus is on the effect of nuclear dissociation below the shock on the linear growth, and nonlinear saturation, of nonradial oscillations of the shocked fluid. We combine two-dimensional, time-dependent hydrodynamic simulations using FLASH2.5 with a solution to the linear eigenvalue problem, and demonstrate the consistency of the two approaches. Previous studies of this 'standing accretion shock instability' (SASI) have focused either on zero-energy accretion flows without nuclear dissociation, or made use of a detailed finite-temperature nuclear equation of state and included strong neutrino heating. Our main goal in this and subsequent papers is to introduce equations of state of increasing complexity, in order to isolate the various competing effects. In this work, we employ an ideal gas equation of state with a constant rate of nuclear dissociation below the shock, and do not include neutrino heating. We find that a negative Bernoulli parameter below the shock significantly lowers the real frequency, growth rate, and saturation amplitude of the SASI. A decrease in the adiabatic index has similar effects. The nonlinear development of the instability is characterized by an expansion of the shock driven by turbulent kinetic energy at nearly constant internal energy. Our results also provide further insight into the instability mechanism: the rate of growth of a particular mode is fastest when the radial advection time from the shock to the accretor overlaps with the period of a standing lateral sound wave. The fastest-growing mode can therefore be modified by nuclear dissociation.},
doi = {10.1088/0004-637X/697/2/1827; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
url = {https://www.osti.gov/biblio/21307916}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 697,
place = {United States},
year = {2009},
month = {6}
}