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Ka Ho Yuen
University of Wisconsin - Madison

Coherent filamentary velocity caustics structures as revealed by the HI, CO, and dust polarization maps near the Taurus region

We present the first study of velocity statistics in the ambient region of Taurus GMC based on the channel maps of HI, CO, and dust maps. Based on the recent development of MHD turbulence theory, Yuen et.al (2021) analytically derive a way in obtaining the velocity caustics map and tested both numerically and observationally. The velocity caustics is filamentary in nature, aligned with the local magnetic field, and follows the Goldreich-Sridhar turbulence, allowing us to retrieve both the statistics of MHD turbulence and the direction of the magnetic field in observation. We extract the velocity caustics from the ambient region of the Taurus GMC and recovers the classic -5/3 Kolmogorov power law from the power spectrum of caustics map from HI, 12CO and 13CO for 3 orders of magnitude, which is not obtainable from the channel map or the column density map. The continuity of the -5/3 power law signifies the continuous velocity cascade from HI and H2. Moreover, we also present the coherent filamentary velocity caustics structures that appear in both HI and CO data and we show their alignment to the B-field as predicted by dust/starlight polarization data. The velocity statistics study marks the onset of the study of spectroscopic data for multiple tracers since the retrieval of velocity caustics is enabled in every spectroscopic data.