DYNAMICS OF A SPHERICAL ACCRETION SHOCK WITH NEUTRINO HEATING AND ALPHA-PARTICLE RECOMBINATION

Journal Article · Thu Oct 01 00:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/703/2/1464· OSTI ID:21371885

Fernandez, Rodrigo ^[1]; Thompson, Christopher ^[2]

---

1. Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada)
2. CITA, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada)

We investigate the effects of neutrino heating and alpha-particle recombination on the hydrodynamics of core-collapse supernovae. Our focus is on the nonlinear dynamics of the shock wave that forms in the collapse and the assembly of positive energy material below it. To this end, we perform time-dependent hydrodynamic simulations with FLASH2.5 in spherical and axial symmetry. These generalize our previous calculations by allowing for bulk neutrino heating and for nuclear statistical equilibrium between n, p, and alpha. The heating rate is freely tunable, as is the starting radius of the shock relative to the recombination radius of alpha-particles. An explosion in spherical symmetry involves the excitation of an overstable mode, which may be viewed as the l = 0 version of the 'Standing Accretion Shock Instability'. In two-dimensional simulations, nonspherical deformations of the shock are driven by plumes of material with positive Bernoulli parameter, which are concentrated well outside the zone of strong neutrino heating. The nonspherical modes of the shock reach a large amplitude only when the heating rate is also high enough to excite convection below the shock. The critical heating rate that causes an explosion depends sensitively on the initial position of the shock relative to the recombination radius. Weaker heating is required to drive an explosion in two dimensions than in one, but the difference also depends on the size of the shock. Forcing the infalling heavy nuclei to break up into n and p below the shock only causes a slight increase in the critical heating rate, except when the shock starts out at a large radius. This shows that heating by neutrinos (or some other mechanism) must play a significant role in pushing the shock far enough out that recombination heating takes over.

• OSTI ID: 21371885
• Journal Information: Astrophysical Journal, Vol. 703, Issue 2; Other Information: DOI: 10.1088/0004-637X/703/2/1464; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
AXIAL SYMMETRY
CONVECTION
COSMIC ALPHA PARTICLES
COSMIC NEUTRINOS
EXCITATION
EXPLOSIONS
HEATING RATE
HEAVY NUCLEI
HYDRODYNAMICS
INSTABILITY
NONLINEAR PROBLEMS
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
RECOMBINATION
SHOCK WAVES
SIMULATION
SUPERNOVAE
TIME DEPENDENCE
TWO-DIMENSIONAL CALCULATIONS
ALPHA PARTICLES
BINARY STARS
CHARGED PARTICLES
COSMIC RADIATION
ELEMENTARY PARTICLES
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
ERUPTIVE VARIABLE STARS
FERMIONS
FLUID MECHANICS
HEAT TRANSFER
IONIZING RADIATIONS
LEPTONS
MASS TRANSFER
MASSLESS PARTICLES
MECHANICS
NEUTRINOS
NUCLEI
PRIMARY COSMIC RADIATION
RADIATIONS
STARS
SYMMETRY
SYNTHESIS
VARIABLE STARS