Advancing the Velocity Gradient Technique: Using Gradient Amplitudes and handling thermal broadening. (arXiv:1802.00024v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Yuen_K/0/1/0/all/0/1">Ka Ho Yuen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lazarian_A/0/1/0/all/0/1">A. Lazarian</a>
The recent development of the Velocity Gradient Technique allows observers to
map magnetic field orientation and magnetization using the direction of
velocity gradients. Aside from the directions, amplitudes of velocity gradients
also contain valuable information that is the subject of this study. Based on
the properties of magneto-hydrodynamic (MHD) turbulence, we explore what
physical information is contained in the amplitudes of velocity gradients and
discuss how this information can be used for the diagnostics of turbulence in
both diffuse and self-gravitating interstellar media. We identify the relation
between amplitudes of both intensity and velocity centroid gradients and the
sonic Mach number $M_s$ and they are consistent with the prediction of the
theory. We test the robustness of the method. We also discuss how to utilize
the amplitudes of gradients into self-gravitating media. To extend the velocity
gradient technique we also discuss to usage of amplitude method to
Position-Position Velocity (PPV) space as a possible way to retrieve the
velocity channel maps not contaminated by thermal broadening. We discuss that
the Velocity Gradient Technique with these advancements could potentially give
a significantly more accurate statistical insight into the properties
magnetized turbulence.
The recent development of the Velocity Gradient Technique allows observers to
map magnetic field orientation and magnetization using the direction of
velocity gradients. Aside from the directions, amplitudes of velocity gradients
also contain valuable information that is the subject of this study. Based on
the properties of magneto-hydrodynamic (MHD) turbulence, we explore what
physical information is contained in the amplitudes of velocity gradients and
discuss how this information can be used for the diagnostics of turbulence in
both diffuse and self-gravitating interstellar media. We identify the relation
between amplitudes of both intensity and velocity centroid gradients and the
sonic Mach number $M_s$ and they are consistent with the prediction of the
theory. We test the robustness of the method. We also discuss how to utilize
the amplitudes of gradients into self-gravitating media. To extend the velocity
gradient technique we also discuss to usage of amplitude method to
Position-Position Velocity (PPV) space as a possible way to retrieve the
velocity channel maps not contaminated by thermal broadening. We discuss that
the Velocity Gradient Technique with these advancements could potentially give
a significantly more accurate statistical insight into the properties
magnetized turbulence.
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