Neutrino transport in supernova models - S[SUB]N[/SUB] method

Yueh, William R.; Buchler, J. R.

doi:10.1086/155605

Cited by 29 publications

(18 citation statements)

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“…The tensor polarization is also included so that "weak magnetism" affects are included to all orders (Horowitz & Pérez-García 2003). The electron scattering rates from Yueh & Buchler (1977) are used for the inelastic scattering kernels. Nucleon scattering is assumed to occur within a single group, although the opacities are calculated using the full inelastic differential cross-sections.…”

Section: Physical Ingredientsmentioning

confidence: 99%

A New Code for Proto-Neutron Star Evolution

Roberts

2012

ApJ

108

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A new code for following the evolution and emissions of proto-neutron stars during the first minute of their lives is developed and tested. The code is one dimensional, fully implicit, and general relativistic. Multi-group, multi-flavor neutrino transport is incorporated that makes use of variable Eddington factors obtained from a formal solution of the static general relativistic Boltzmann equation with linearized scattering terms. The timescales of neutrino emission and spectral evolution obtained using the new code are broadly consistent with previous results. Unlike other recent calculations, however, the new code predicts that the neutrino-driven wind will be characterized, at least for part of its existence, by a neutron excess. This change, potentially consequential for nucleosynthesis in the wind, is due to an improved treatment of the charged-current interactions of electron flavored neutrinos and anti-neutrinos with nucleons. A comparison is also made between the results obtained using either variable Eddington factors or simple equilibrium flux-limited diffusion. The latter approximation, which has been frequently used in previous studies of proto-neutron star cooling, accurately describes the total neutrino luminosities (to within 10%) for most of the evolution, until the proto-neutron star becomes optically thin.

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Section: Physical Ingredientsmentioning

confidence: 99%

A New Code for Proto-Neutron Star Evolution

Roberts

2012

ApJ

108

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“…Variable Eddington moments of the neutrino phase space distribution are used for closing the moment equations, and the integrodifferential character of the Boltzmann equation is tamed by using the zeroth and first order angular moments (neutrino density and flux) in the source terms on the right hand side of the Boltzmann equation. This numerical approach is fundamentally different from the so-called S N methods (Carlson 1967;Yueh & Buchler 1977;Mezzacappa & Bruenn 1993a;Yamada et al 1999) which employ a direct discretization of the Boltzmann equation in all variables including the dependence on the angular direction of the radiation propagation.…”

Section: Boltzmann Solvers For Neutrino Transportmentioning

confidence: 99%

Radiation hydrodynamics with neutrinos

Rampp

Janka

2002

A&A

392

555

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Abstract. Neutrino transport and neutrino interactions in dense matter play a crucial role in stellar core collapse, supernova explosions and neutron star formation. Here we present a detailed description of a new numerical code for treating the time and energy dependent neutrino transport in hydrodynamical simulations of such events. The code is based on a variable Eddington factor method to deal with the integro-differential character of the Boltzmann equation. The moments of the neutrino distribution function and the energy and lepton number exchange with the stellar medium are determined by iteratively solving the zeroth and first order moment equations in combination with a model Boltzmann equation. The latter is discretized on a grid of tangent rays. The integration of the transport equations and the neutrino source terms is performed in a time-implicit way. In the present version of the program, the transport part is coupled to an explicit hydrodynamics code which follows the evolution of the stellar plasma by a finite-volume method with piecewise parabolic interpolation, using a Riemann solver to calculate the hydrodynamic states. The neutrino source terms are implemented in an operator-split step. Neutrino transport and hydrodynamics can be calculated with different spatial grids and different time steps. The structure of the described code is modular and offers a high degree of flexibility for an application to relativistic and multi-dimensional problems at different levels of refinement and accuracy. We critically evaluate results for a number of test cases, including neutrino transport in rapidly moving stellar media and approximate relativistic core collapse, and suggest a path for generalizing the code to be used in multi-dimensional simulations of convection in neutron stars and supernovae.

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“…(A1) for Ye and T using implicit equilibrium energies and under the simplifying assumption that the neutrino fluxes vanish. Inelastic scattering of (all types of) neutrinos off electrons and positrons is implemented as in Yueh & Buchler (1977); Bruenn (1985); Rampp & Janka (2002), i.e. using a Legendre expansion in the scattering angle of neutrinos up to 1st order.…”

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confidence: 99%

“…using a Legendre expansion in the scattering angle of neutrinos up to 1st order. For the multidimensional generalization of the formalism of Yueh & Buchler (1977); Bruenn (1985); Rampp & Janka (2002) (who assumed spherical symmetry and therefore vanishing non-radial flux-vector components and non-diagonal Eddington-tensor components) we use the expressions given in Cernohorsky (1994). We obtain the Legendre coefficients of up to 1st order for each initial-state and final-state neutrino energy and each neutrino species by table interpolation.…”

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confidence: 99%

Core-collapse supernova simulations in one and two dimensions: comparison of codes and approximations

Just

Bollig

Janka

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present spherically symmetric (1D) and axisymmetric (2D) supernova simulations for a convection-dominated 9 M and a 20 M progenitor that develops violent activity by the standing-accretion-shock instability (SASI). We compare in detail the Aenus-Alcar code, which uses fully multidimensional two-moment neutrino transport with an M1 closure, with a ray-by-ray-plus (RbR+) version of this code and with the Prometheus-Vertex code that employs RbR+ two-moment transport with a Boltzmann closure. Besides testing consequences of ignored non-radial neutrino-flux components in the RbR+ approximation, we also discuss the influence of various transport ingredients applied or not applied in recent literature, namely simplified neutrino-pair processes, neutrino-electron scattering, velocity-dependent and gravitational-redshift terms, and strangeness and many-body corrections for neutrino-nucleon scattering. Alcar and Vertex show excellent agreement in 1D and 2D despite a slightly but systematically smaller radius (∼1 km) and stronger convection of the proto-neutron star with Alcar. As found previously, the RbR+ approximation is conducive to explosions, but much less severely in the convection-dominated 9 M case than in the marginally exploding 20 M model, where the onset time of explosion also exhibits big stochastic variations, and the RbR+ approximation has no distinctly stronger supportive effect than simplified pair processes or strangeness and many-body corrections. Neglecting neutrino-electron scattering has clearly unfavorable effects for explosions, while ignoring velocity and gravitational-redshift effects can both promote or delay the explosion. The ratio of advection timescale to neutrino-heating timescale in 1D simulations is a sensitive indicator of the influence of physics ingredients on explosions also in multidimensional simulations.

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Neutrino transport in supernova models - S[SUB]N[/SUB] method

Cited by 29 publications

References 0 publications

A New Code for Proto-Neutron Star Evolution

A New Code for Proto-Neutron Star Evolution

Radiation hydrodynamics with neutrinos

Core-collapse supernova simulations in one and two dimensions: comparison of codes and approximations

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