On the polarimetric signature of emerging magnetic loops in the quiet-Sun

TL;DR

This study confirms that Stokes V profiles dominated by one lobe are a key polarimetric signature of emerging magnetic loops in the quiet Sun, with a higher occurrence than in the general quiet-Sun regions.

Contribution

It demonstrates that one-lobe dominated Stokes V profiles are a reliable indicator of emerging magnetic loops, supporting previous physical models and suggesting a new observational proxy.

Findings

47% of profiles have amplitude asymmetry > 0.3 at emergence sites

Compared to 30% in general quiet-Sun regions, indicating a significant excess

Supports the use of Stokes V asymmetry as a proxy for magnetic loop emergence

Abstract

The abundance of Stokes V profiles dominated by one lobe at the locations of emergence of Omega-shaped magnetic loops is evaluated. The emergence events were found in Hinode SOT/SP time-sequences of quiet-Sun regions. Such a study has the aim of confirming a prediction based on the basic geometrical and physical properties of emerging magnetic loops: Stokes V profiles dominated by one lobe are possibly the main polarimetric signature of these structures. In agreement with this prediction, 47 % of the Stokes V profiles analyzed has an unsigned amplitude asymmetry larger than 0.3, while in the quiet-Sun the abundance is of about 30 %. This excess with respect to the quiet-Sun is found consistently for whatever value of the threshold on the amplitude asymmetry. Such a result proves the goodness of the physical scenarios so far proposed for the interpretation of loop emergence events and may prompt the use of Stokes V profiles dominated by one lobe as a new proxy for their identification in observations with a good spectral sampling.