http://arxiv.org/abs/1604.06102
We extend the analysis of the fluctuations in the velocity slices of Position-Position- Velocity (PPV) spectroscopic data from Doppler broadened lines, i.e. Velocity Channel Analysis (VCA) introduced by Lazarian & Pogosyan (2000), to study anisotropy of the underlying velocity and density turbulence statistics that arises from the presence of magnetic field. In particular, we study analytically how the measurable anisotropy of the statistics of the channel map fluctuations changes with the thickness of velocity channels. In agreement with the earlier VCA studies we find that the anisotropy of the thick channels reflects the anisotropy of the density field, while the relative contribution of density and velocity fluctuations to the thin velocity channels depends on the density spectral slope. We show that the anisotropies arising from Alfven, slow and fast modes are different, in particular, the anisotropy in PPV created by fast modes is opposite to that created by Alfven and slow modes and this can be used to separate their contributions. We successfully compare our results with the earlier numerical study of the PPV anisotropies measured with synthetic observations in Esquivel et al. 2015. We also obtain the anisotropies for the media with absorption as well as for the absorption lines. In addition, we demonstrate how the studies of anisotropy can be performed using interferometers.
D. Kandel, A. Lazarian and D. Pogosyan
Fri, 22 Apr 16
51/54
Comments: 36 pages, 16 figures, submitted to MNRAS
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