TeV Emission from the Galactic Center Black-Hole Plerion

The HESS collaboration recently reported the detection of TeV γ-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 ∼ 100MeV electrons emanates from an inefficiently radiating turbulent magnetized corona within 20 RS (Schwarzschild radii) of the GCBH. Electrons are accelerated in this ADAF through second-order Fermi processes by MHD turbulence, as suggested by Liu et al. (2004). Closer to the innermost stable orbit of the ADAF, instabilities and shocks within the flow inject power-law electrons through firstorder Fermi acceleration to make synchrotron X-ray flares observed with Chandra, XMM, and INTEGRAL. A subrelativistic MHD wind subtending an ∼ 1 sr cone with power & 10 erg s is driven by the ADAF from the vicinity of the GCBH. Electrons accelerated at the wind termination shock at & 10 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 yrs, could explain the origin of the nonthermal radio emission in the two-sided bar of the radio nebula Sgr A West. Subject headings: acceleration of particles—black hole physics—Galaxy: center—plasmas—radiation processes: nonthermal