Relativistic outflows from advection-dominated accretion disks around black holes

Advection-dominated accretion flows (ADAFs) have a positive Bernoulli param eter and are therefore gravitationally unbound. The Newtonian ADAF model ha s been generalized recently to obtain the ADIOS model that includes outflow s of energy and angular momentum, thereby allowing accretion to proceed sel f-consistently. However, the utilization of a Newtonian gravitational poten tial limits the ability of this model to describe the inner region of the d isk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a pseudo-Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self-similar solution for the structure of the coupled disk/wind s ystem. Interesting features of the new solution include the relativistic ch aracter of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Hence, our self-similar solution may help to explain the origin of relativi stic jets in active galaxies. At large distances the radial dependence of t he accretion rate approaches the unique form (M) over dot proportional to r (1/2), with an associated density variation given by rho proportional to r( -1). This density variation agrees with that implied by the dependence of t he hard X-ray time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the predictions made usin g our self-similar solution need to be confirmed in the future using a deta iled model that includes a physical description of the energization mechani sm that drives the outflow, which is likely to be powered by the shear of t he underlying accretion disk.