Exploring the X1.0 flare on 2014 Mar 29 via non-force-free-field extrapolation and its MHD evolution

We have investigated the X1.0 flare, peaked at 17:48 UT on 2014 March 29 in NOAA AR12017, a well-known flare in the solar cycle 24. Our focus lies on the magnetic topologies encompassing the flaring region especially on the MHD evolution during the eruption. For this purpose, we have obtained the initial magnetic field using the non-force-free-field (NFFF) extrapolation technique which is different from the contemporary force-free-field models. The equation of motion derived in NFFF is based on the minimum dissipation rate (MDR) principle, which is proved to be very efficient for the open system like solar corona. The key criterion in the NFFF approximation is the photosphere having non-zero Lorentz force which will drive the plasma from the initial state in the MHD evolution. Then we proceed with extrapolation using the photospheric vector magnetogram of Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO). From extrapolated magnetic field, in the proximity of the flaring region, we have found one three dimensional positive null, a set of twisted magnetic field lines aka the magnetic flux ropes and a set of sheared arcades in between them. Additionally, we have calculated the twist value and it is significant near the flux ropes with respect to the non-flaring region. In order to understand the initiation process and the dynamics during the event, we have performed a data-constrained simulation using the EULAG-MHD model from the extrapolated field. Interesting is the dynamics found in the topologies. The reconnections near the null point facilitate the eruption. Furthermore, the dynamics of the flux ropes and the sheared arcades seems to be favourable towards breakout type of eruption. Also, the potential loops generated after the eruption are seen to be collocated with the post reconnection loops in 94 A channel of Atmospheric Imaging Assembly (AIA)/SDO. Although this event has been studied observationally from a multitude of aspects, the dynamics via MHD simulation is a few. Hence, we have attempted to explore the possible eruption mechanism using a unique extrapolation method and its subsequent simulation.