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T. Le, P. A. Becker (Center of Earth Observing and Space Research, and Department of Physics and Astronomy, George Mason University)
Observations have shown that relativistic jets are commonly associated with radio-loud Active Galatic Nuclei (AGNs). The original Advection-Dominated Accretion Flow (ADAF) model developed by Narayan & Yi has had some success in explaining the X-ray emission from Sgr~A* and several other AGNs that are underluminous in X-rays. However, the ADAF model does not include any mass loss from the accretion disk, and consequently it cannot account for the formation of relativistic outflows in the radio-loud sources. Some generalization of the original ADAF scenario is therefore required in order to explain the formation of the outflows. In this paper we develop a new ADAF/outflow scenario using the standard fluid conservation equations, modified to include the escape of mass, energy, and angular momentum from the disk due to the outflow. The model also includes a transport equation to simulate the acceleration of relativistic protons in the disk due to second-order Fermi acceleration in the shearing, turbulent magnetic field. The relativistic protons (and attendant electrons)escape from the disk to form the outflow, which starts as a hot wind and accelerates to reach a terminal Lorentz factor ~10, in agreement with observations of jets. We will discuss the results obtained and the significance for our understanding of underluminous black-hole accretion.
The author(s) of this abstract have provided an email address for comments about the abstract: tle@scs.gmu.edu