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A new iterative method for non-LTE multilevel polarized radiative transfer in hydrogen lines is presented. Iterative methods (such as the Jacobi method) tend to damp out high-frequency components of the error fast, but converges poorly due…

Astrophysics · Physics 2008-11-26 Jiri Stepan

In the present paper we consider the full nonlocal thermodynamic equilibrium (non-LTE) radiation transfer problem. This formalism allows us to account for deviation from equilibrium distribution of both the radiation field and the massive…

Solar and Stellar Astrophysics · Physics 2024-10-09 M. Sampoorna , F. Paletou , V. Bommier , T. Lagache

Most of the physical information about astrophysical objects is obtained via the analysis of their electromagnetic spectra. Observed data coupled with radiation transfer models in physical conditions representative of stars, planets,…

Solar and Stellar Astrophysics · Physics 2026-05-29 Maria Bergemann , Richard Hoppe

Higher resolution telescopes as well as 3D numerical simulations will require the development of detailed 3D radiative transfer calculations. Building upon our previous work we extend our method to include both continuum and line transfer.…

Astrophysics · Physics 2009-11-13 E. Baron , Peter H. Hauschildt

Recently, with the advances in computational speed and availability there has been a growth in the number and resolution of fully 3-D hydrodynamical simulations. However, all of these simulations are purely hydrodynamical and there has been…

Astrophysics · Physics 2009-11-10 E. Baron , Peter H. Hauschildt

The so-called full non-local thermodynamic equilibrium (FNLTE) radiative transfer problem allows us to take into account not only deviations of the radiation field from the Planckian but also deviations of the densities and velocity…

Solar and Stellar Astrophysics · Physics 2026-05-14 T. Lagache , M. Sampoorna , F. Paletou

A revised and greatly improved version of the 3D continuum radiative transfer code MC3D is presented. It is based on the Monte-Carlo method and solves the radiative transfer problem self-consistently. It is designed for the simulation of…

Astrophysics · Physics 2009-11-07 Sebastian Wolf

The linearly-polarized solar limb spectrum that is produced by scattering processes contains a wealth of information on the physical conditions and magnetic fields of the solar outer atmosphere, but the modeling of many of its strongest…

Solar and Stellar Astrophysics · Physics 2015-05-18 M. Sampoorna , J. Trujillo Bueno

Resonance spectral lines such as H I Ly {\alpha}, Mg II h&k, and Ca II H&K that form in the solar chromosphere are influenced by the effects of 3D radiative transfer as well as partial redistribution (PRD). So far no one has modeled these…

Solar and Stellar Astrophysics · Physics 2016-12-28 Andrii V. Sukhorukov , Jorrit Leenaarts

Context: The solution of the nonlocal thermodynamical equilibrium (non-LTE) radiative transfer equation usually relies on stationary iterative methods, which may falsely converge in some cases. Furthermore, these methods are often unable to…

Solar and Stellar Astrophysics · Physics 2015-07-29 Julien Lambert , Eric Josselin , Nils Ryde , Alexandre Faure

State-of-the-art methods in multidimensional NLTE radiative transfer are based on the use of local approximate lambda operator within either Jacobi or Gauss-Seidel iterative schemes. Here we propose another approach to the solution of 2D…

Solar and Stellar Astrophysics · Physics 2015-06-18 Ivan Milic , Olga Atanackovic

A new, very fast method for 3D radiative transfer on fully threaded grids with arbitrarily high angular resolution is presented. The method uses completely cell-based discretization, and is ideally suited for problems with diffuse…

Astrophysics · Physics 2009-11-11 A. O. Razoumov , C. Y. Cardall

We discuss an implementation of our 3D radiative transfer (3DRT) framework with the OpenCL paradigm for general GPU computing. We implement the kernel for solving the 3DRT problem in Cartesian coordinates with periodic boundary conditions…

Instrumentation and Methods for Astrophysics · Physics 2011-08-01 Peter H. Hauschildt , E. Baron

This study concerns the fast and accurate solution of the line radiation transfer problem, under non-LTE conditions. We propose and evaluate an alternative iterative scheme to the classical ALI-Jacobi method, and to the more recently…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 F. Paletou , E. Anterrieu

3D detailed radiative transfer is computationally taxing, since the solution of the radiative transfer equation involves traversing the six dimensional phase space of the 3D domain. With modern supercomputers the hardware available for…

Solar and Stellar Astrophysics · Physics 2021-02-05 Peter H. Hauschildt , E. Baron

A solution of the radiative-transfer problem in arbitrary velocity fields introduced in a previous paper, has limitations in its applicability. For large-scale applications, the methods described also require large memory sets that are…

Solar and Stellar Astrophysics · Physics 2009-09-24 S. Knop , P. H. Hauschildt , E. Baron

In network and active region plages, the magnetic field is concentrated into structures often described as flux tubes (FTs) and sheets (FSs). 3-D radiative transfer (RT) is important for energy transport in these concentrations. It is also…

Solar and Stellar Astrophysics · Physics 2015-06-11 R. Holzreuter , S. K. Solanki

We present benchmark problems and solutions for the continuum radiative transfer (RT) in a 2D disk configuration. The reliability of three Monte-Carlo and two grid-based codes is tested by comparing their results for a set of well-defined…

Astrophysics · Physics 2009-11-10 I. Pascucci , S. Wolf , J. Steinacker , C. P. Dullemond , Th. Henning , G. Niccolini , P. Woitke , B. Lopez

When integrating the radiative transfer equation for polarized light, the necessity of high-order numerical methods is well known. In fact, well-performing high-order formal solvers enable higher accuracy and the use of coarser spatial…

Solar and Stellar Astrophysics · Physics 2017-09-06 Gioele Janett , Oskar Steiner , Luca Belluzzi

We propose in this work a Monte Carlo method for three dimensional scalar radiative transfer equations with non-integrable, space-dependent scattering kernels. Such kernels typically account for long-range statistical features, and arise…

Numerical Analysis · Mathematics 2023-07-19 Christophe Gomez , Olivier Pinaud