Returning magnetic flux in sunspot penumbrae

TL;DR

This study reveals reversed magnetic polarity flux in sunspot penumbrae using a novel regularized deconvolution method and spectropolarimetric data analysis, uncovering reversed fields at bright filament borders.

Contribution

Introduces a new regularization technique based on principal component decomposition for deconvolving spectropolarimetric data to study magnetic fields.

Findings

Reversed polarity magnetic fields are present at the borders of bright penumbral filaments.

First detection of reversed polarity fields across the entire penumbra.

Method successfully infers magnetic field vectors from deconvolved spectropolarimetric data.

Abstract

We study the presence of reversed polarity magnetic flux in sunspot penumbra. We applied a new regularized method to deconvolve spectropolarimetric data observed with the spectropolarimeter SP onboard Hinode. The new regularization is based on a principal component decomposition of the Stokes profiles. The resulting Stokes profiles were inverted to infer the magnetic field vector using SIR. We find, for the first time, reversed polarity fields at the border of many bright penumbral filaments in the whole penumbra.