Magnetic Energy Dissipation during the 2014 March 29 Solar Flares

TL;DR

This study tracks the evolution of magnetic free energy during the 2014 March 29 X-class solar flare using multi-wavelength observations, revealing consistent energy measurements across different atmospheric layers and demonstrating the detectability of vertical electric currents.

Contribution

It introduces a method to measure magnetic free energy from both chromospheric and coronal tracers, confirming their consistency and the ability to detect vertical electric currents during solar flares.

Findings

Peak free energy of approximately 45 x 10^{30} erg.

Energy decrease of about 29 x 10^{30} erg during decay.

Consistent free energy measurements across EUV and UV wavelengths.

Abstract

We calculated the time evolution of the free magnetic energy during the 2014-Mar-29 flare (SOL2014-03-29T17:48), the first X-class flare detected by IRIS. The free energy was calculated from the difference between the nonpotential field, constrained by the geometry of observed loop structures, and the potential field. We use AIA/SDO and IRIS images to delineate the geometry of coronal loops in EUV wavelengths, as well as to trace magnetic field directions in UV wavelengths in the chromosphere and transition region. We find an identical evolution of the free energy for both the coronal and chromospheric tracers, as well as agreement between AIA and IRIS results, with a peak free energy of $E_{free}(t_{peak}) \approx (45 \pm 2) \times 10^{30}$ erg, which decreases by an amount of $\Delta E_{free} \approx (29 \pm 3) \times 10^{30}$ erg during the flare decay phase. The consistency of free energies measured from different EUV and UV wavelengths for the first time here, demonstrates that vertical electric currents (manifested in form of helically twisted loops) can be detected and measured from both chromospheric and coronal tracers.