PORTA (POlarized Radiative TrAnsfer)

PORTA logo designed by Jiri Stepan

PORTA (POlarized Radiative TrAnsfer) is a radiative transfer code for the simulation of the spectral line intensity and polarization caused by scattering processes and the Hanle and Zeeman effects in 3D models of stellar atmospheres.

 

Summary

PORTA comes with several modules useful for considering some problems of interest for the planning and interpretation of spectropolarimetric observations with the present and new generation of solar telescopes, as well as with a user-friendly interface to visualize the results. It can be applied to solve the non-LTE problem of the generation and transfer of polarized radiation in three-dimensional (3D) Cartesian models of stellar atmospheres, taking fully into account the symmetry breaking effects produced by the model’s horizontal inhomogeneities and macroscopic velocity gradients. The present version can be applied to model the intensity and polarization of spectral lines (i.e., the four Stokes parameters) within the framework of the equations for the multilevel atom model described in chapter 7 of Landi Degl’Innocenti & Landolfi (2004), which assume complete frequency redistribution. The user can perform a variety of radiative transfer numerical experiments, taking into account either the combined action of anisotropic radiation pumping and the Hanle and Zeeman effects, only scattering processes and the Hanle effect, or just the impact of the Zeeman effect, on the polarization of the emergent spectral line radiation. The parallelization strategy of PORTA facilitates the numerical solution of complex 3D radiative transfer problems using massively parallel supercomputers.
The public version of PORTA is one of the objectives of the POLMAG research project. PORTA is under continuous development and new features and modules will be implemented, such as a developer manual. To keep track of such developments we invite the interested users to subscribe to the PORTA mailing list (see section 9.1 of the documentation). We offer it to the astrophysical community with the hope that it is applied for achieving new advances in solar and stellar spectropolarimetry.

 

References

The main reference for the code that you should give when publishing papers using PORTA is:

Download

The code is freely available to the community, hosted at GitLab. The latest version of PORTA can be found at https://gitlab.com/polmag/PORTA, and the latest version of the documentation at https://polmag.gitlab.io/PORTA/.