Lunch talk on Mar. 15, 2021

Predicting CMB Foreground Dust Polarization with Velocity Gradients

Speaker: Yue Hu (University of Wisconsin-Madison)

Venue: Video conference

Time: 12:30 PM, Monday, Mar. 15, 2021

Abstract: 

Observations of fluctuations in the cosmic microwave background provide information about primordial inhomogeneities in the universe. However, the inflationary gravitational wave's B-mode polarization is contaminated by the Galactic foreground polarized radiation arising from dust aligned by interstellar magnetic fields. Fortunately, recent studies show that analysis of velocity gradients (the Velocity Gradients Technique; VGT) can be used to trace the magnetic field morphology employing the anisotropic nature of magnetohydrodynamic turbulent motions. Our studies show that VGT is applicable for both transparent diffuse gas and dense molecular gas. With the Galactic rotation curve's assistance, we obtain the 3D map of the galactic disk plane-of-the-sky magnetic field distribution. Using multiple molecular emission lines, which trace various volume density ranges, we find the possibility of constructing 3D magnetic fields tomography in a molecular cloud. Additionally, probing magnetic fields in galaxy clusters is challenging, especially on large scales outside of individual radio sources. We give the VGT-predicted magnetic field morphology of the Perseus, M 87, Coma, and A2597 galaxy clusters utilizing the Chandra X-ray images.

Report PPT:  SWIFAR_Yue Hu.pdf