On the Sensitivity of the H$\alpha$ Scattering Polarization to Chromospheric Magnetism

TL;DR

This paper demonstrates that the Hanle effect in Hα can be used to quantitatively probe the magnetic fields of the quiet solar chromosphere, overcoming limitations of intensity profile insensitivity.

Contribution

It introduces a method to analyze the Hanle effect in Hα for measuring chromospheric magnetism, providing a new diagnostic tool.

Findings

Response function of scattering polarization to magnetic perturbations calculated

Hanle effect in Hα offers quantitative magnetic diagnostics

Chromospheric magnetism can be probed independently of intensity profiles

Abstract

A particularly interesting line for exploring the physical conditions of the quiet solar chromosphere is H$\alpha$, but its intensity profile is magnetically insensitive and the small circular polarization signatures produced by the longitudinal Zeeman effect come mainly from the underlying photosphere. Here we show that the Hanle effect in H$\alpha$ provides quantitative information on the magnetism of the quiet chromosphere. To this end, we calculate the response function of the emergent scattering polarization to perturbations in the magnetic field.