Synchrotron Intensity and Polarization Gradients: Tools to Obtain the Magnetization Level in a Turbulent Medium

Abstract

Abstract Synchrotron intensity and polarization gradients (SIG and SPG), proposed by Lazarian et al. and Lazarian & Yuen, present a new way to recover the mean magnetic field direction in the plane of the sky. To measure the magnetization level, Lazarian et al. suggested that the methods used in the context of the “Velocity Gradient Technique” could also be used on the SIG and SPG contexts. In this work we test the two proposed methods, named “top-base” and the circular standard deviation, “S,” to obtain the level of magnetization from synchrotron emission. In order to test the methods, we generate synthetic observations from magnetohydrodynamic computer simulations, with Alfvénic Mach numbers, M A ∈ [0.2,1.7]. Using a Bayesian analysis we find that the circular standard deviations for the SIG and SPG methods are able to recover the magnetization for cases with signal-to-noise ratio ≳5. We found that for weak Faraday depolarization and different angles between the magnetic field direction and the line of sight the magnetization level can still be estimated.