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Accurate angular quadratures are crucial for the numerical solution of three-dimensional (3D) radiative transfer problems, especially when the spectral line polarisation produced by the scattering of anisotropic radiation is included. There…

Solar and Stellar Astrophysics · Physics 2021-01-27 Jaume Jaume Bestard , Jiří Štěpán , Javier Trujillo Bueno

The integro-differential formulation of the RTE and its solution by iterations on the source has been extended here to handle anisotropic scattering. The iterative part of the method is O(N ln N ), thanks to an efficient use of H-matrices.…

Numerical Analysis · Mathematics 2023-06-12 Olivier Pironneau , Pierre-Henri Tournier

Superlevel partitioning is combined with a simple relaxation procedure to construct an iterative technique for solving equations of statistical equilibrium. In treating an $N$-level model atom, the technique avoids the $N^{3}$ scaling in…

Astrophysics · Physics 2009-11-06 L. B. Lucy

We present new detailed NLTE calculations for model atmospheres of novae during outburst. This fully self-consistent NLTE treatment for a number of model atoms includes 3922 NLTE levels and 47061 NLTE primary transitions. We discuss the…

Astrophysics · Physics 2009-10-30 Peter H. Hauschildt , Steven N. Shore , Greg J. Schwarz , E. Baron , S. Starrfield

In order to constrain the models describing circumstellar environments, it is necessary to solve the radiative transfer equation in the presence of absorption and scattering, coupled with the equation for radiative equilibrium. However,…

Solar and Stellar Astrophysics · Physics 2021-09-29 Jérémy Perdigon , Gilles Niccolini , Marianne Faurobert

The double detonation is a widely discussed explosion mechanism for Type Ia supernovae, whereby a helium shell detonation ignites a secondary detonation in the carbon/oxygen core of a white dwarf. Even for modern models that invoke…

We describe an extension of the Enzo code to enable fully-coupled radiation hydrodynamical simulation of inhomogeneous reionization in large $\sim (100 Mpc)^3$ cosmological volumes with thousands to millions of point sources. We solve all…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Michael L. Norman , Daniel R. Reynolds , Geoffrey C. So , Robert P. Harkness , John H. Wise

Earlier studies have suggested that deviations from the local thermodynamic equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. Recent improvements in the atomic data allow…

Solar and Stellar Astrophysics · Physics 2022-01-12 S. Korotin , A. Kučinskas

Nuclear implementation of the density functional theory (DFT) is at present the only microscopic framework applicable to the whole nuclear landscape. The extension of DFT to superfluid systems in the spirit of the Kohn-Sham approach, the…

Nuclear Theory · Physics 2021-08-24 Shi Jin , Kenneth J. Roche , Ionel Stetcu , Ibrahim Abdurrahman , Aurel Bulgac

We introduce Monte Carlo-based non-LTE line radiative transfer calculations in the 3D dust radiative transfer code SKIRT, which was originally set up as a dust radiative transfer code. By doing so, we develop a generic and powerful 3D…

Astrophysics of Galaxies · Physics 2023-10-25 Kosei Matsumoto , Peter Camps , Maarten Baes , Frederik De Ceuster , Keiichi Wada , Takao Nakagawa , Kentaro Nagamine

A novel 3-D higher-order finite-difference time-domain framework with complex frequency-shifted perfectly matched layer for the modeling of wave propagation in cold plasma is presented. Second- and fourth-order spatial approximations are…

Plasma Physics · Physics 2013-10-25 Konstantinos P. Prokopidis

The rapid growth of LLMs demands high-throughput, memory-capacity-intensive inference on resource-constrained edge devices, where single-batch decoding remains fundamentally memory-bound. Existing out-of-core GPU-based and SSD-like…

Hardware Architecture · Computer Science 2026-04-29 Mingbo Hao , Changwei Yan , Haoyu Cui , Zhihao Yan , Yizhi Ding , Zhangrui Qian , Weiwei Shan

We present an accurate quadrature formula on the sphere with less localized quadrature points for efficient numerical computation of the radiative transport equation (RTE) in the three dimensions. High accuracy of the present method…

Numerical Analysis · Mathematics 2014-09-02 Hiroshi Fujiwara

X-ray scatter has been a serious concern in computed tomography (CT), leading to image artifacts and distortion of CT values. The linear Boltzmann transport equation (LBTE) is recognized as a fast and accurate approach for scatter…

Medical Physics · Physics 2025-08-29 Guoxi Zhu , Li Zhang , Zhiqiang Chen , Hewei Gao

The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…

Statistical Mechanics · Physics 2009-11-11 Michael J. Caola

A finite element method for solving the resonance line transfer problem in moving media is presented. The algorithm works in three spatial dimensions on unstructured grids which are adaptively refined by means of an a posteriori error…

Astrophysics · Physics 2009-11-07 E. Meinkoehn , S. Richling

We develop a time-dependent multi-group multidimensional relativistic radiative transfer code, which is required to numerically investigate radiation from relativistic fluids involved in, e.g., gamma-ray bursts and active galactic nuclei.…

Instrumentation and Methods for Astrophysics · Physics 2015-09-09 Nozomu Tominaga , Sanshiro Shibata , Sergei I. Blinnikov

A comprehensive model atom was developed for Si I-II-III using the most up-to-date atomic data available so far. Based on the non-local thermodynamic equilibrium (non-LTE = NLTE) line formation for Si I, Si II, and Si III and…

Solar and Stellar Astrophysics · Physics 2020-04-08 Lyudmila Mashonkina

We investigate statistical equilibrium of neutral and singly-ionized strontium in late-type stellar atmospheres. Particular attention is given to the completeness of the model atom, which includes new energy levels, transition…

Solar and Stellar Astrophysics · Physics 2015-06-05 M. Bergemann , C. J. Hansen , M. Bautista , G. Ruchti

We present a new approach to numerically model continuum radiative transfer based on the Optically Thin Variable Eddington Tensor (OTVET) approximation. Our method insures the exact conservation of the photon number and flux (in the…

Astrophysics · Physics 2009-11-06 Nickolay Y. Gnedin , Tom Abel
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