Spectropolarimetric Diagnostics at the Solar Photosphere near the Limb

TL;DR

This study uses 3-D radiation-MHD simulations to analyze Stokes profiles near the solar limb, comparing synthetic spectra with high-resolution observations to improve spectropolarimetric diagnostics of active regions.

Contribution

It introduces a method to generate and degrade synthetic Stokes spectra from simulations, closely matching observational data for better diagnostics near the solar limb.

Findings

Synthetic spectra roughly reproduce observed spectro-polarimetric signals.

Flux tubes with kilo-Gauss fields dominate the active region plage.

Degraded synthetic data match high-resolution observations at Mu=0.39.

Abstract

In the present work, we investigate the formation of Stokes profiles and spectro-polarimetric diagnostics in an active region plage near the limb. We use 3-D radiation-MHD simulations with unipolar fields of an average strength of 400 G, which is largely concentrated in flux tubes in which the field reaches typical kilo-Gauss values. We generate synthetic Stokes spectra by radiative transfer calculations, then we degrade the simulated Stokes signal to account for observational conditions. The synthetic data treated in this manner are compared with and found to roughly reproduce spectro-polarimetric high-resolution observations at Mu=0.39 obtained by the SOUP instrument with the Swedish 1-m Solar Telescope at the beginning of 2006.