Authors: Jonathan Lee (Institute for Astronomy, University of Hawaii at Manoa), Xudong Sun (Institute for Astronomy, University of Hawaii at Manoa), Tibor Török (Predictive Science Inc.), Cooper Downs (Predictive Science Inc.), Jon Linker (Predictive Science Inc.)

Here we use a “helicity pumping” method to estimate the maximum possible magnetic energy that could be stored in NOAA active region (AR) 11158 prior to its X2.2 flare. We first use the recently developed Regularized Biot-Savart Law (RBSL) flux rope construction model paired with a zero-beta  magnetohydrodynamic (MHD) simulation to create a configuration consisting of a potential field and a magnetic flux rope. The  “helicity pumping” method is used to iteratively energize the stable configuration towards eruption. The maximum magnetic energy storage on the cusp of eruption is then estimated and contrasted with the initial MHD relaxation. Pumping helicity uniformly within the modeled volume yields a 3.5% increase in total magnetic energy from the initial relaxed state. When helicity pumping was instead localized centrally over the Polarity Inversion Line (PIL) straddled by the flux rope footpoints, total magnetic energy increased by 5.8% from the initial state. Future work includes making estimates of the magnetic helicity prior to eruption. Applying these methods to a sample of ARs will allow us to set a theoretical upper limit to the free energy and helicity for a given surface magnetic distribution: eruption will be inevitable if a realistic energy/helicity estimate exceeds the threshold.