Estimating electric current densities in solar active regions

TL;DR

This paper introduces a new method to estimate vertical electric current densities in solar active regions from vector magnetogram data, accounting for uncertainties and noise, aiding magnetic field modeling.

Contribution

A novel approach for estimating $J_z$ that incorporates measurement uncertainties and minimizes current density squared across active regions.

Findings

Method effectively estimates $J_z$ with noisy data

Demonstrated on a twisted bipole model

Provides improved boundary conditions for magnetic modeling

Abstract

Electric currents in solar active regions are thought to provide the energy released via magnetic reconnection in solar flares. Vertical electric current densities $J_z$ at the photosphere may be estimated from vector magnetogram data, subject to substantial uncertainties. The values provide boundary conditions for nonlinear force- free modelling of active region magnetic fields. A method is presented for estimating values of $J_z$ taking into account uncertainties in vector magnetogram field values, and minimizing $J_z^2$ across the active region. The method is demonstrated using the boundary values of the field for a force-free twisted bipole, with the addition of noise at randomly chosen locations.