Three-lobed near-infrared Stokes V profiles in the quiet Sun

TL;DR

This study analyzes complex three-lobed Stokes V profiles in the quiet Sun's photosphere using spectropolarimetric data and inversion techniques to understand the magnetic and kinematic structures responsible.

Contribution

It introduces two inversion approaches to interpret multi-lobed polarization signals, revealing co-existing strong and weak magnetic fields with opposite polarities within the resolution element.

Findings

Presence of co-existing strong and weak magnetic fields with opposite polarities.

Both inversion methods suggest interlaced magnetic and flow structures.

Complex magnetic topology responsible for three-lobed Stokes V profiles.

Abstract

We investigate a region of the quiet solar photosphere exhibiting three-lobed Stokes V profiles in the Fe I spectral line at 15648 Angstroem. The data were acquired with the GRIS spectropolarimeter attached to the GREGOR telescope. We aim at investigating the thermal, kinematic and magnetic properties of the atmosphere responsible for these measured complex signals. The SIR inversion code is employed to retrieve the physical parameters of the lower solar photosphere from the observed polarization signals. We follow two different approaches. On the one hand, we consider that the multi-lobe circular polarization signals are only produced by the line-of-sight variation of the physical parameters. We therefore invert the data assuming a single atmospheric component that occupies the entire resolution element in the horizontal plane and where the physical parameters vary with optical depth (i.e., line-of-sight). On the other hand, we consider that the multi-lobe circular polarization signals are produced not by the optical depth variations of the physical parameters but instead by their horizontal variations. Here we invert the data assuming that the resolution element is occupied by two different atmospheric components where the kinematic and magnetic properties are constant along the line-of-sight. Both approaches reveal some common features about the topology responsible for the observed three-lobed Stokes V signals: both a strong (>1000 Gauss) and a very weak (< 10 Gauss) magnetic field with opposite polarities and harboring flows directed in opposite directions must co-exist (either vertically or horizontally interlaced) within the resolution element.