http://arxiv.org/abs/2102.08882
We extend a neutrino transport approximation, called Advanced Spectral Leakage (ASL), with the purpose of modeling neutrino-driven winds in neutron star mergers. Based on a number of snapshots we gauge the ASL parameters by comparing against both the two-moment (M1) scheme implemented in the FLASH code and the Monte Carlo neutrino code Sedonu. The ASL scheme contains three parameters, the least robust of which results to be a blocking parameter for electron neutrinos and anti-neutrinos. The parameter steering the angular distribution of neutrino heating is re-calibrated compared to the earlier work (arXiv:1906.11494). We also present a new, fast and mesh-free algorithm for calculating spectral optical depths, which, when using Smoothed Particle Hydrodynamics (SPH), makes the neutrino transport completely particle-based. We estimate a speed-up of a factor of $\gtrsim 100$ in the optical depth calculation when comparing to a grid-based approach. In the suggested calibration we recover luminosities and mean energies within $25\%$. A comparison of the rates of change of internal energy and electron fraction in the neutrino-driven wind suggests comparable accuracies of ASL and M1, but a higher computational efficiency of the ASL scheme. We estimate that the ratio between the CPU hours spent on the ASL neutrino scheme and those spent on the hydrodynamics is $\lesssim 0.8$ per timestep when considering MAGMA2 (arXiv:1911.13093) as source code for the Lagrangian hydrodynamics, to be compared with a factor of 10 from the M1 in FLASH.
D. Gizzi, C. Lundman, E. O’Connor, et. al.
Thu, 18 Feb 21
43/66
Comments: 20 pages, 17 figures, 3 tables
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