A Novel Mechanism of the Formation of Electron-Positron Outflow
from Hot Accretion Disks
A mechanism is proposed
for the formation of relativistic outflows
in active galactic nuclei and Galactic black hole binaries,
i.e., the ejection of electron-positron pairs
produced in two-temperature accretion disks in these objects.
We investigate the pair production processes in the accretion disks,
coupled with the pair ejection
by solving the disk structure equations, including the
vertical momentum equation of the electron-positron pairs,
within the one-zone approximation.
We assume that
the electron-positron component can escape independently of
the electron-proton one
which forms a hydrostatic atmosphere.
The results show that, in the inner region of the disks,
when the mass accretion rate becomes larger than
about a tenth of the Eddington rate,
most of the viscously dissipated energy is converted
into the thermal and kinetic energy of the ejected electron-positron pairs.
Furthermore, the produced pairs are accelerated in the vertical direction
by their own gas pressure rather than by the radiative force.
This result means that the outflow energy is not supplied
by the radiation field,
but by the thermal energy of the electron-positron pairs
which comes from protons through Coulomb collisions.
It solves the difficulty explaining the observational fact of high power
of jets in models that the pairs are produced and accelerated outside of
This mechanism is, thus, successful in extracting accretion-power
to form powerful electron-positron outflows as suggested by recent observations
of active galactic nuclei and Galactic objects.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.