Seminar by Yue Hu, UW-Madison
MHD turbulence and magnetic field are two of the most essential elements in the multi-phase ISM. They crucially regulate cosmic ray propagation, star formation, and galaxy evolution , but are challenging to study. The presentation will focus on the anisotropic nature of MHD turbulence, using 3D two-fluid simulations generated with the AthenaK code. Specifically, the talk will show that the neutral-ion decoupling scale is smaller than earlier considered. The collisional interaction of ions and neutrals leads to the damping of turbulence. The anisotropy of MHD turbulence also provides a novel method to trace the magnetic field in galaxies. Based on high-resolution CO isotopolog data from the ALMA and the PAWS survey, magnetic field maps traced by the anisotropy for nearby galaxies M51 and NGC 1097 will be presented. Comparison of the magnetic fields inferred from CO data, SOFIA/HAWC+, and VLA reveals rich information about Seyfert activity. The presentation will show a local misalignment between the magnetic fields traced by CO and HAWC+ 89um dust polarization within the nuclear ring of NGC 1097. This misalignment serves as an observational diagnostic for the ongoing multiphase fueling of Seyfert activity and indicates different magnetic field configurations in different gas phases. Overall, the seminar talk will shed light on the anisotropic nature of MHD turbulence and its implications for the study of magnetic fields in galaxies.
Host: Luca Comisso