Origin of the Fermi bubble

Fermi has discovered two giant gamma-ray-emitting bubbles that extend nearly 10kpc in diameter north and south of the Galactic center. The existence of the bubbles was first evidenced in X-rays detected by ROSAT and later WMAP detected an excess of radio signals at the location of the gamma-ray bubbles. We propose that periodic star capture processes by the galactic supermassive black hole, Sgr A*, with a capture rate 3 × 10^-5 yr ^-1 and energy release ∼3 × 10⁵² erg per capture can produce very hot plasma ∼10 keV with a wind velocity ∼10⁸ cm s^-1 injected into the halo and heat up the halo gas to ∼1 keV, which produces thermal X-rays. The periodic injection of hot plasma can produce shocks in the halo and accelerate electrons to ∼TeV, which produce radio emission via synchrotron radiation and gamma rays via inverse Compton scattering with the relic and the galactic soft photons.