Fermi Bubble Z.G.,Xiong

Outline Observations Theories Simulations Discussion

Observations Finkbeiner,2004

Bland-Hawthorn & Cohen, 2003

Su et al.,2010

Characteristics: size symmetry uniform common origin morphology spectrum

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

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.

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.

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∗

AGN Jet Guo，2011 we show that the bubbles can be created with a recent AGN jet activity about 1 - 3 Myr ago, which was active for a duration of ∼ 0.1 - 0.5 Myr Roles of viscosity and cosmic ray diffusion

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.

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

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

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

Simulation AGN Jet Equations

The Galactic Model

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

Shock stucture:

Proton spectrum

Electron spectrum

Space distribution

Interactions between shocks:

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

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