Velocity Centroids Anisotropy and the Signature of different MHD Modes
  in the Turbulent ISM
  Magnetic turbulence is anisotropic as the directions of motion are
constrained by the magnetic field. Such anisotropy can be observed in velocity
centroids obtained from spectroscopic observations. We use magnetohydrodynamics
(MHD) simulations to produce synthetic spectroscopic observations
(position-position-velocity data) and study the anisotropy in the structure
function of velocity centroid maps. We decomposed the velocity in the
simulations into Alfv\'en, slow and fast-modes and studied how each of them
contribute to the observed anisotropy. We found that when the angle between the
line of sight and the mean magnetic field is large the Alfv\'en-mode dominates
the observed anisotropy, while for smaller angles the anisotropy is not large
enough to be used to probe the magnetization of the media, and it is dominated
by the slow-mode. Our results are in fair agreement with the theoretical
predictions in Kandel et al.(2016,2017).
