2006   2008   2010   2012   2014   2016   2018   2020  
2006   2008   2010   2012   2014   2016   2018   2020
The MPIA conference series
at Ringberg Castle
The MPIA conference series
at Ringberg Castle
 
EPoS 2020 Suggested Contribution
Studying Magnetic Fields and Dynamics of Star formation with Velocity Gradients

Alex Lazarian
UW-Madison, Madison, US
Due to the advances in understanding of MHD turbulence and turbulent reconnection we formulated a new Velocity Gradient Technique (VGT) of magnetic field tracing. The technique has been successfully tested using high resolution numerical simulations as well as by comparing with magnetic field maps obtained with the with Planck satellite and BLASTPOL polarimetry. In my talk I am going to focus on new prospects that the VGT presents in terms of exploring (a) the 3D structure of magnetic fields in molecular clouds, (b) the magnetic connection of dense and diffuse gas and (c) the dynamics of the gravitational collapse. The latter possibility is illustrated, on the basis of numerical simulations, in Figure 1. There it is shown that how to identify using the VGT the regions of gravitational collapse as well as to trace magnetic field. I will show of survey of nearby molecular clouds where both magnetic fields and regions of gravitational collapse are identified using the VGT. In addition, I shall show the 3D magnetic structure of Vela C molecular cloud that is obtained by applying the VGT to different molecular species that are formed at different optical depths. Finally, I shall describe a new technique that demonstrates high precision in obtaining the strength of magnetic fields using the VGT. Using numerical data, I will demonstrate that the new technique can provide the magnetic field strength in the regions strongly affected by self-gravity where the classical Davis-Chandrasekhar-Fermi technique fails. I will show the results for magnetic field strength obtained for nearby molecular clouds.
Caption: Numerical simulations with velocity gradients shown in panel (a) and by dust polarization assuming perfect grain alignment in panel (b). Panels (b) and (e) provide the zoom-in into a high-density star-forming region. Panel (c) illustrates the procedure of identifying the regions of gravitational collapse by identifying the double peaks of gradient distribution. Panel (d) illustrated the texture map of magnetic field obtained after turning velocity gradients 90 degrees within the identified region of gravitational collapse.
Key publication

Suggested Session: Magnetic Fields