Two-dimensional multiangle, multigroup neutrino radiation-hydrodynamic simulations of postbounce supernova cores
We perform axisymmetric (2D) multiangle, multigroup neutrino radiation-hydrodynamic calculations of the postbounce phase of core-collapse supernovae using a genuinely 2D discrete-ordinate (S_n) method. We follow the long-term postbounce evolution of the cores of one nonrotating and one rapidly rotating 20 M_⊙ stellar model for ~400 milliseconds from 160 to ~550 ms after bounce. We present a multidimensional analysis of the multiangle neutrino radiation fields and compare in detail with counterpart simulations carried out in the 2D multigroup flux-limited diffusion (MGFLD) approximation to neutrino transport. We find that 2D multiangle transport is superior in capturing the global and local radiation-field variations associated with rotation-induced and SASI-induced aspherical hydrodynamic configurations. In the rotating model, multiangle transport predicts much larger asymptotic neutrino flux asymmetries with pole-to-equator ratios of up to ~2.5, while MGFLD tends to sphericize the radiation fields already in the optically semi-transparent postshock regions. Along the poles, the multiangle calculation predicts a dramatic enhancement of the neutrino heating by up to a factor of 3, which alters the postbounce evolution and results in greater polar shock radii and an earlier onset of the initially rotationally weakened SASI. In the nonrotating model, differences between multiangle and MGFLD calculations remain small at early times when the postshock region does not depart significantly from spherical symmetry. At later times, however, the growing SASI leads to large-scale asymmetries and the multiangle calculation predicts up to 30% higher average integral neutrino energy deposition rates than MGFLD.
Additional Information© Institute of Physics and IOP Publishing Limited 2008. Received 2008 March 31; accepted 2008 June 24. We acknowledge helpful discussions with and input from Jeremiah Murphy, Ivan Hubeny, Casey Meakin, Jim Lattimer, Alan Calder, Stan Woosley, Ed Seidel, Harry Dimmelmeier, H.-Thomas Janka, Kei Kotake, Thierry Foglizzo, Ewald Muller, Bernhard Muller, Martin Obergaulinger, Benjamin D. Oppenheimer, Thomas Marquart, and Erik Schnetter. This work was partially supported by the Scientific Discovery through Advanced Computing (SciDAC) program of the US Department of Energy under grants DE-FC02-01ER41184 and DE-FC02- 06ER41452. C. D. O. acknowledges support through a Joint Institute for Nuclear Astrophysics postdoctoral fellowship, subaward 61-5292UA of NFS award 86-6004791. E. L. acknowledges support by the Israel Science Foundation (grant 805/04). The computations were performed at the local Arizona Beowulf cluster, on the Columbia SGI Altix machine at the Ames center of the NASA High End Computing Program, at the National Center for Supercomputing Applications (NCSA) under Teragrid computer time grant TG-MCA02N014, at the Center for Computation and Technology at Louisiana State University, and at the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US Department of Energy under contract DE-AC03-76SF00098.
Published - OTTapj08.pdf