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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
We present results from high-resolution semi-global simulations of
neutrino-driven convection in core-collapse supernovae. We employ an idealized
setup with parametrized neutrino heating/cooling and nuclear dissociation at
the shock front. We study the internal dynamics of neutrino-driven convection
and its role in re-distributing energy and momentum through the gain region. We
find that even if buoyant plumes are able to locally transfer heat up to the
shock, convection is not able to create a net positive energy flux and overcome
the downwards transport of energy from the accretion flow. Turbulent convection
does, however, provide a significant effective pressure support to the
accretion flow as it favors the accumulation of energy, mass and momentum in
the gain region. We derive an approximate equation that is able to explain and
predict the shock evolution in terms of integrals of quantities such as the
turbulent pressure in the gain region or the effects of non-radial motion of
the fluid. We use this relation as a way to quantify the role of turbulence in
the dynamics of the accretion shock. Finally, we investigate the effects of
grid resolution, which we change by a factor 20 between the lowest and highest
resolution. Our results show that the shallow slopes of the turbulent kinetic
energy spectra reported in previous studies are a numerical artefact.
Kolmogorov scaling is progressively recovered as the resolution is increased.
