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Mapping of the structure of the galactic magnetic field with velocity gradients: Test using star light polarization

Research paper by Diego F. Gonzalez-Casanova, A. Lazarian

Indexed on: 25 May '18Published on: 25 May '18Published in: arXiv - Astrophysics - Astrophysics of Galaxies



Abstract

We apply Velocity Channel Gradients (VChGs) and Reduced Velocity Centroids Gradients (RVCGs) to Hi data (the LAB survey) and get the plane of the sky component of the magnetic field as a function of the relative velocity. Assuming a galactic rotation curve, we transformed the relative velocities to distances, constructing the first map of the galactic 3D magnetic field. To test the accuracy of our 3D distribution we used a set of stars with known distances from the stellar polarization (Heiles 2000) catalog and compared the polarization directions that we obtain with our 3D magnetic field map with the actual starlight polarization directions. We find a good correspondence between the expected and measured polarization directions which testify of the accuracy of the new way of probing the 3D galactic magnetic field structure.