3D magnetic field observations associated with filamentary molecular clouds

In this talk, I will briefly discuss our work on understanding the 3D morphology of magnetic fields associated with molecular clouds. To study the 3D magnetic fields, we first proposed and demonstrated a new technique to determine the line-of-sight strength and direction of magnetic fields associated with molecular clouds based on Faraday rotation measurements. We applied this method to four relatively nearby filamentary molecular clouds. For three of these clouds, we found that the line-of-sight magnetic field reverses across them (from one side of the cloud to the other along the short axis of the filament).

We then used these line-of-sight and Planck’s plane-of-sky magnetic field observations along with models and statistical tools to study the 3D morphology of the magnetic field associated with the Orion A cloud.  Additionally, we used Galactic magnetic field models and velocity information to reconstruct the overall (and coherent) magnetic field morphologies of the Perseus and Orion A clouds, including their signed direction (without 180 deg ambiguity). In this talk I will discuss these techniques and our results.