The Fermi Bubbles as Starburst Wind Termination Shocks
  The enhanced star formation in the inner 100 pc of the Galaxy launches a
superwind at ~1600 km s$^{-1}$ for M82-like parameters. The ram pressure of the
wind is very low compared to more powerful starburst winds. I show that halo
gas stops the wind a few kpc from the Galactic Centre. I suggest that the
termination shock accelerates cosmic rays, and that the resulting Inverse
Compton gamma rays are visible as the Fermi Bubbles. The Bubbles are then wind
bubbles, which the starburst can inflate within 10 Myr. They can remain in
steady state as long as the starburst lasts. The shock may accelerate PeV
electrons and EeV protons. The Bubbles may be analogues of galactic wind
termination shocks in the intergalactic medium. I discuss the advantages and
problems of this model. I note that any jets from Sgr A* must burrow through
the starburst wind bubble before reaching the halo gas, which could affect the
early evolution of such jets.
