TeV Emission from the Galactic Center Black-Hole Plerion

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  • 9 October 2004
Abstract
The HESS collaboration recently reported the detection of TeV gamma-ray emission coincident with Sgr A*. In the context of other Galactic Center (GC) observations, this points to the following scenario: In the extreme advection-dominated accretion flow (ADAF) regime of the GC black hole (BH), synchrotron radio/sub-mm emission of ~100 MeV electrons emanates from an inefficiently radiating turbulent magnetized corona within 20 Schwarzschild radii of the GCBH. Electrons are accelerated in this ADAF through second-order Fermi processes by MHD turbulence. Closer to the innermost stable orbit of the ADAF, instabilities and shocks within the flow inject power-law electrons through first-order Fermi acceleration to make synchrotron X-ray flares observed with Chandra, XMM, and INTEGRAL. A subrelativistic MHD wind subtending an ~1sr cone with power ~10^{37} erg/s is driven by the ADAF from the vicinity of the GCBH. Electrons accelerated at the wind termination shock at >~ 10^{16.5} cm from the GCBH Compton-scatter ADAF and FIR dust emission to TeV energies. The synchrotron radiation of these electrons produces the quiescent X-ray plerionic source resolved by Chandra. The radio counterpart of the TeV/X-ray plerion, formed when the injected electrons cool on timescales of \~10^4 yrs, could explain the origin of the nonthermal radio emission in the two-sided bar of the radio nebula Sgr A West.

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