The Velocity Centroids Gradients for Absorbing Media [GA]

We explore the application of the Velocity Gradient Technique, new way to trace magnetic fields in the plane of the sky, to an absorbing media for the case of $^{13}$CO~2-1 emission. Using MHD turbulence simulations, we calculate the velocity gradient using velocity centroids and an improved procedure for calculating gradients suggested by Yuen & Lazarain. We find that the velocity centroid gradients trace the projected magnetic field in media with different CO abundances, densities and optical depths. We also explore how the calculations of the magnetic field strengths, which employs the dispersion of the velocity gradient, is modified in the presence of self-absorption. Our study opens up the possibility to use velocity centroid gradients to trace magnetic fields using $^{13}$CO~2-1 emission.

Read this paper on arXiv…

D. Gonzalez-Casanova, A. Lazarian and B. Burkhart
Fri, 10 Mar 17

Comments: 8 pages , 6 figures