Scattering polarization and the Hanle effect in H-alpha as a probe of chromospheric magnetism: Modeling vs. Observations

TL;DR

This study combines modeling and observations to demonstrate that the scattering polarization of H-alpha is highly sensitive to chromospheric magnetic fields, revealing abrupt magnetization in the upper quiet Sun chromosphere.

Contribution

It provides new spectropolarimetric observations and radiative transfer modeling showing the sensitivity of H-alpha polarization to chromospheric magnetic fields.

Findings

H-alpha scattering polarization is highly sensitive to magnetic field strength and structure.

Observations suggest an abrupt increase in magnetization in the upper chromosphere.

Modeling indicates a significant magnetic influence on polarization profiles.

Abstract

The Hanle effect in strong spectral lines is the physical mechanism that should be increasingly exploited for quantitative explorations of the magnetism of the quiet solar chromospheric plasma. Here we show, by means of multilevel radiative transfer calculations and new spectropolarimetric observations, that the amplitude and shape of the scattering polarization profiles of the H-alpha line is very sensitive to the strength and structure of the chromospheric magnetic field. The interpretation of the observations in terms of one-dimensional radiative transfer modeling suggests that there is an abrupt magnetization in the upper chromosphere of the quiet Sun.