Open AccessReconstructing the Coronal Magnetic Field: The Role of Cross-field Currents in Solution Uniqueness
Author(s) -
Nathaniel H. Mathews,
Natasha Flyer,
S. E. Gibson
Publication year - 2020
Publication title -
astrophysical journal/the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.3847/1538-4357/ab9dfd
Subject(s) - physics , magnetic field , computational physics , field (mathematics) , magnetohydrodynamics , uniqueness , dipole model of the earth's magnetic field , plasma , l shell , classical mechanics , mechanics , earth's magnetic field , interplanetary magnetic field , mathematical analysis , solar wind , quantum mechanics , mathematics , pure mathematics
We present a new 3D magnetohydrostatic (MHS) direct elliptic solver for extrapolating the coronal magnetic field from photospheric boundary conditions in a manner consistent with an assumed plasma distribution. We use it to study the uniqueness of the reconstructed magnetic field as a function of how significant the plasma forcing is on the force balance of the magnetic field. To this end, we consider an analytic MHS model as ground truth. The model uses two free parameters to decompose the current into two parts: a magnetic-field-aligned component and a cross-field component. We perform a comprehensive study of the 2D parameter space to understand under what conditions the ground truth can be reproduced uniquely. We find that current oriented perpendicular to the magnetic field has a smaller solution space than the same amount of current oriented parallel to the magnetic field, and so MHS regimes with larger proportions of plasma-related forcing may be a promising avenue toward finding unique magnetic field reconstructions.