Speaker: Yue Hu (UW-Madison)

Title: Characterizing 3D Magnetic Fields in Star-Forming Regions

Magnetic field, turbulence, and self-gravity are important in understanding star formation. However, 3D magnetic field orientation and strength were barely accessed. Based on our recent understanding of dust polarization and anisotropic MHD turbulence, I will present two novel methods, i.e., polarization fraction analysis and velocity gradient technique (VGT), in tracing the 3D magnetic field orientation. By combing with the Davis–Chandrasekhar-Fermi method, I will show that the 3D magnetic field distribution, including both orientation and strength, is successfully recovered in the low-mass star-forming region L1688. The second method, VGT employs spectroscopic emission lines to derive the magnetic field. I will show that VGT-measurement advantageously gets rid of the contribution from the cloud’s foreground/background. By using multiple molecular tracers, VGT reveals the magnetic field’s variation in different volume density regimes. I will also discuss magnetic fields’ role in fueling galactic nuclei.