Study of single-lobed circular polarization profiles in the quiet Sun

TL;DR

This study investigates the properties, spatial distribution, and physical origins of single-lobed circular polarization profiles in the quiet Sun, revealing their association with magnetic flux emergence and submergence processes through observations, inversions, and simulations.

Contribution

First comprehensive analysis of single-lobed Stokes V profiles in the quiet Sun, combining observations, inversions, and 3D simulations to understand their physical origins.

Findings

Single-lobed profiles occupy about 2% of the solar surface.

Profiles are linked to magnetic flux emergence/submergence.

Synthetic profiles agree with observations, supporting inferred magnetic topologies.

Abstract

The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere is known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight, possibly associated with gradients of magnetic field strength, inclination and/or azimuth. We have focused our study on the Stokes V profiles showing extreme asymmetry in the from of only one lobe. Using Hinode spectropolarimetric measurements we have performed a statistical study of the properties of these profiles in the quiet sun. We show their spatial distribution, their main physical properties, how they are related with several physical observables and their behavior with respect to their position on the solar disk. The single lobed Stokes V profiles occupy roughly 2% of the solar surface. For the first time, we have observed their temporal evolution and have retrieved the physical conditions of the atmospheres from which they emerged using an inversion code implementing discontinuities of the atmospheric parameters along the line of sight. In addition, we use synthetic Stokes profiles from 3D magnetoconvection simulations to complement the results of the inversion. The main features of the synthetic single-lobed profiles are in general agreement with the observed ones, lending support to the magnetic and dynamic topologies inferred from the inversion. The combination of all these different analysis suggests that most of the single-lobed Stokes V profiles are signals coming from magnetic flux emergence and/or submergence processes taking place in small patches in the photospheric of the quiet sun.