A new MHD-assisted Stokes inversion technique

Bibliographic Details
Title: A new MHD-assisted Stokes inversion technique
Authors: Riethmüller, T. L., Solanki, S. K., Barthol, P., Gandorfer, A., Gizon, L., Hirzberger, J., van Noort, M., Rodríguez, J. Blanco, Iniesta, J. C. Del Toro, Suárez, D. Orozco, Schmidt, W., Pillet, V. Martínez, Knölker, M.
Publication Year: 2016
Collection: Astrophysics
Subject Terms: Astrophysics - Solar and Stellar Astrophysics
More Details: We present a new method of Stokes inversion of spectropolarimetric data and evaluate it by taking the example of a SUNRISE/IMaX observation. An archive of synthetic Stokes profiles is obtained by the spectral synthesis of state-of-the-art magnetohydrodynamics (MHD) simulations and a realistic degradation to the level of the observed data. The definition of a merit function allows the archive to be searched for the synthetic Stokes profiles that match the observed profiles best. In contrast to traditional Stokes inversion codes, which solve the Unno-Rachkovsky equations for the polarized radiative transfer numerically and fit the Stokes profiles iteratively, the new technique provides the full set of atmospheric parameters. This gives us the ability to start an MHD simulation that takes the inversion result as initial condition. After a relaxation process of half an hour solar time we obtain physically consistent MHD data sets with a target similar to the observation. The new MHD simulation is used to repeat the method in a second iteration, which further improves the match between observation and simulation, resulting in a factor of 2.2 lower mean $\chi^2$ value. One advantage of the new technique is that it provides the physical parameters on a geometrical height scale. It constitutes a first step towards inversions giving results consistent with the MHD equations.
Comment: Accepted for publication in the Astrophysical Journal on Nov. 15 2016 (part of the Sunrise2 special issue)
Document Type: Working Paper
DOI: 10.3847/1538-4365/aa5830
Access URL: http://arxiv.org/abs/1611.05175
Accession Number: edsarx.1611.05175
Database: arXiv
More Details
DOI:10.3847/1538-4365/aa5830