The AGN Jet Model of the Fermi Bubbles
  The nature and origin of the Fermi bubbles detected in the inner Galaxy
remain elusive. In this paper, we briefly discuss some recent theoretical and
observational developments, with a focus on the AGN jet model. Analogous to
radio lobes observed in massive galaxies, the Fermi bubbles could be naturally
produced by a pair of opposing jets emanating nearly along the Galaxy's
rotation axis from the Galactic center. Our two-fluid hydrodynamic simulations
reproduce quite well the bubble location and shape, and interface instabilities
at the bubble surface could be effectively suppressed by shear viscosity. We
briefly comment on some potential issues related to our model, which may lead
to future progress.
