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The Fermi Bubbles: Possible Nearby Laboratory for AGN Jet Activity
Yang, Hsiang-Yi Karen ( University of Michigan ); Ruszkowski, M. ( University of Michigan ); Zweibel, E. G. ( University of Wisconsin-Madison ); Ricker, P. M. ( University of Illinois ) show affiliations
American Astronomical Society, HEAD meeting #13, #300.02
Published in Apr 2013
The two giant gamma-ray bubbles discovered by the Fermi Gamma-ray Space Telescope are nearly symmetric about the Galactic plane, suggesting some episode of energy injection from the Galactic center, such as a nuclear starburst or active galactic nucleus (AGN) jet activity. Using three-dimensional magnetohydrodynamic simulations that self-consistently include the dynamical interaction between cosmic rays (CR) and thermal gas, and anisotropic CR diffusion along magnetic field lines, we show that the key characteristics of the observed bubbles can be successfully reproduced by a recent jet activity from the central AGN. This implies that the Fermi bubbles could be a unique laboratory for studying AGN jet-inflated bubbles. Our simulations allow us to generate maps of the distribution of the magnetic field, radio polarization, and synchrotron, X-ray, and gamma-ray emission. While the source of pressure support of extragalactic AGN bubbles is still poorly known due to observational limitations, we are able to derive constraints on the composition of the Fermi bubbles by comparing our model predictions with the spatially resolved gamma-ray bubble and microwave haze observations.
(c) 2013: American Astronomical Society