Evolution of Disk Angular Momentum in Triaxial Dark Matter Halos

Galactic halos are believed to form through both the early inflow of dark matter from the cosmic web and mergers over and extended period. At the same time, stellar disks are forming within this evolving halo. How a stellar disk responds to a changing halo is investigated in this study using live n-body disks embedded in an analytic triaxial potential. At triaxialities of a few percent, we find that while there are subtle perturbations in the disk, there is no significant change in the total disk angular momentum. However, between 5 and 10\% triaxialities there is a sharp transition to a strong disk tilt. This angular momentum evolution is observed to occur in our models after a delay of about half a Hubble-time.