Optimization of Magnetic Flux Ropes Modeled with the RBSL method

Abstract

The so-called regularized Biot-Savart laws (RBSLs) provide an efficient and flexible method for modeling pre-eruptive magnetic configurations of coronal mass ejections (CMEs) whose characteristics are constrained by observational images and magnetic-field data. This method allows one to calculate the field of magnetic flux ropes (MFRs) with small circular cross-sections and an arbitrary axis shape. The field of the whole configuration is constructed as a superposition of (1) such a flux-rope field and (2) an ambient potential field derived, for example, from an observed magnetogram. The RBSL kernels are determined from the requirement that the MFR field for a straight cylinder must be exactly force-free. For a curved MFR, however, the magnetic forces are generally unbalanced over the whole path of the MFR. To minimize these forces, we apply a modified Gauss-Newton method to find optimal MFR parameters. This is done by iteratively adjusting the MFR axis path and axial current. We then try to relax the resulting optimized configuration in a subsequent line-tied zero-beta magnetohydrodynamic simulation toward a force-free equilibrium. By considering two models of the sigmoidal pre-eruption configuration for the 2009 February 13 CME, we demonstrate how this approach works and what it is capable of. We show, in particular, that the building blocks of the core magnetic structure described by these models match to morphological features typically observed in such type of configurations. Our method will be useful for both the modeling of particular eruptive events and theoretical studies of idealized pre-eruptive MFR configurations.

21 pages, 11 figures, accepted to ApJS

References in corpus (12)

• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• Observation of An Evolving Magnetic Flux Rope Prior To and During A Solar Eruption
• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• Generalized Squashing Factors for Covariant Description of Magnetic Connectivity in the Solar Corona
• Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars
• Three-Dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
• Flux Rope Formation Preceding Coronal Mass Ejection Onset
• Simulating the in situ condensation process of solar prominences
• Determining the Intrinsic CME Flux Rope Type Using Remote-sensing Solar Disk Observations
• Regularized Biot-Savart Laws for Modeling Magnetic Flux Ropes
• MHD simulation of prominence-cavity system
• 2010 August 1-2 sympathetic eruptions: II. Magnetic topology of the MHD background field

Cited by in corpus (5)

• STITCH: A Subgrid-Scale Model for Energy Buildup in the Solar Corona
• Writhed Analytical Magnetic Flux Rope Model
• Filament Eruption Driving EUV Loop Contraction then Expansion above a Stable Filament
• A Magnetogram-matching Method for Energizing Magnetic Flux Ropes Toward Eruption
• Magnetogram-matching Biot-Savart Law and Decomposition of Vector Magnetograms