Nucleosynthesis-relevant conditions in neutrino-driven supernova outflows

II. The reverse shock in two-dimensional simulations

¹ Department of PhysicsUniversity of Basel, Klingelbergstraße 82, 4056 Basel, Switzerland
e-mail: a.arcones@unibas.ch
² Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85741 Garching, Germany

Received: 4 August 2010
Accepted: 4 December 2010

Abstract

After the initiation of the explosion of core-collapse supernovae, neutrinos emitted from the nascent neutron star drive a supersonic baryonic outflow. This neutrino-driven wind interacts with the more slowly moving, earlier supernova ejecta forming a wind termination shock (or reverse shock), which changes the local wind conditions and their evolution. Important nucleosynthesis processes (alpha-process, charged-particle reactions, r-process, and νp-process) occur or might occur in this environment. The nucleosynthesis depends on the long-time evolution of density, temperature, and expansion velocity. Here we present two-dimensional hydrodynamical simulations with an approximate description of neutrino-transport effects, which for the first time follow the post-bounce accretion, onset of the explosion, wind formation, and the wind expansion through the collision with the preceding supernova ejecta. Our results demonstrate that the anisotropic ejecta distribution has a great impact on the position of the reverse shock, the wind profile, and the long-time evolution. This suggests that hydrodynamic instabilities after core bounce and the consequential asymmetries may have important effects on the nucleosynthesis-relevant conditions in the neutrino-heated baryonic mass flow from proto-neutron stars.