1. Fermi Bubble
Z.G.,Xiong

2. Outline
Observations
Theories
Simulations
Discussion

4. Observations
Finkbeiner,2004

5. Bland-Hawthorn & Cohen, 2003

6. Su et al.,2010

7. Characteristics: size symmetry uniform common origin morphology
spectrum

8. Theories Bipolar Galactic wind Echoes of the Last Quasar Outburst
AGN Jet
Cosmic Rays Reservoirs
Star Capture

9. Bipolar Galactic wind Bland-Hawthorn，2002
In accord with the stellar record in the Galactic Center, we infer that a powerful nuclear starburst has taken place within the last several million years
We infer that the Galactic Center is driving large-scale winds into the halo every ∼ 10 − 15 Myr or so.

10. Echoes of the Last Quasar Outburst Zubovas,2011
Here we propose an alternative picture where the bubbles are the remnants of a large–scale wide–angle outflow from the SMBH of our Galaxy.
the well known star formation event in the inner 0.5pc of the Milky Way 6 Myr ago.

11. We estimate that an accreted mass 2 × 10^3M⊙ is needed for the accretion event to power the observed Fermi–LAT lobes.
This estimate suggests that roughly 50% of the gas was turned into stars, while the rest accreted onto Sgr A∗

12. AGN Jet
Guo，2011
we show that the bubbles can be created with a recent AGN jet activity about Myr ago, which was active for a duration of ∼ Myr
Roles of viscosity and cosmic ray diffusion

13. Giant, Multi-Billion-Year-Old Reservoirs of Galactic Center Cosmic Rays
Crocker,2011
Here we show that the bubbles are naturally explained as due to a population of relic cosmic ray protons and heavier ions injected by processes associated with extremely long timescale (> 8 Gyr) and high areal density star-formation in the Galactic center.

14. Fermi Bubbles as a Result of Star Capture in the Galactic Center
Dogiel,2011; Cheng,2011; Chernyshov,2011.

15. processes of star capture by the central black hole
Dogiel et al. (2009d).

16. Star capture by the central black hole
Plasma heating by subrelativistic protons
The hydrodynamic expansion stage
Shock wave acceleration phase and non-thermal emission

17. Simulation
AGN Jet
Equations

18. The Galactic Model

21. Star Capture
Parameters:
the tidal disruption rate;
power; …

22. Shock stucture:

23. Proton spectrum

24. Electron spectrum

25. Space distribution

26. Interactions between shocks:

27. Discussion Young or old? Leptonic or baryonic? Common? Impact
Regulation for CRs

28. Thank you!