  Using a method based on Faraday rotation measurements, Tahani et al. 2018
find the line-of-sight component of magnetic fields in Orion-A and show that
their direction changes from the eastern side of this filamentary structure to
its western side. Three possible magnetic field morphologies that can explain
this reversal across the Orion-A region are toroidal, helical, and bow-shaped
morphologies. In this paper we construct simple models to represent these three
morphologies and compare them with the available observational data to find the
most probable morphology(ies). To compare the observations with the models, we
use probability values and a Monte-Carlo analysis to determine the most likely
magnetic field morphology among these three morphologies. We find that the bow
morphology has the highest probability values and that our Monte-Carlo analysis
suggests that the bow morphology is more likely. We suggest that the bow
morphology is the most likely and the most natural of the three morphologies
that could explain a magnetic field reversal across the Orion-A filamentary
structure (i.e., bow, helical and toroidal morphologies).
