Bayesian approach for modeling global magnetic parameters of solar active regions

MARIANO POISSON; MARCELO LÓPEZ FUENTES; CRISTINA H. MANDRINI; FRANCISCO GRINGS; PASCAL DÉMOULIN

Montevideo

Congreso; XVII Latin American IAU Meeting; 2023

International Astronomical Union

Active regions (ARs) appear in the solar atmosphere as the consequence of the emergence of magnetic flux tubes formed in the solar interior. Several observational evidence, models and simulations have shown that these coherent structures must carry magnetic helicity, forming magnetic flux ropes (FRs). Since these FRs are the most important means by which magnetic energy is transported out to the solar atmosphere, its study is fundamental to fully comprehend energy release processes such as flares and coronal mass ejections. However, acquiring precise estimations of their intrinsic magnetic parameters during the early phase of the ARs evolution is limited to the observed photospheric magnetic flux distribution. In particular, the observed line-of-sight (LOS) component of the photospheric magnetic field can be affected by the amount of twist on these FRs producing a departure of the expected symmetric bipolar configuration. In this work, we aim to model the magnetic parameters of emerging FRs using a Bayesian scheme. We model the 3D structure of the FR with a magnetic field with a geometry defined by a half-torus with uniform torsion. This 8-parameter model can produce a sequence of synthetic LOS magnetograms by projecting the vertical component over transversal planes at different heights relative to the center of the torus. We perform the inference over a sequence of LOS magnetograms of four different emerging ARs. We test and compare submodels in which different temporal correlation of the parameters are considered. We found that the inferred magnetic parameters such as the magnetic helicity and tilt angle obtained for all the studied ARs are consistent with other previous estimations.