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INFLUENCE OF
OHMIC HEATING ON ADVECTION-DOMINATED ACCRETION FLOWS
Authors:
G.S. Bisnovatyi-Kogan, and R.V.E. Lovelace
Advection-dominated, high-temperature, quasi-spherical accretion flow
onto a compact object, recently considered by a number of authors, assume that the
dissipation of turbulent energy of the flow heats the ions and that the dissipated energy
is advected inward. It is suggested that the efficiency of conversion of accretion energy
to radiation can be very much smaller than unity. However, it is likely that the flows
have an equipartition magnetic field with the result that dissipation of magnetic energy
at a rate comparable to that for the turbulence must occur by Ohmic heating. We argue that
this heating occurs as a result of plasma instabilities and that the relevant
instabilities are current driven in response to the strong electric fields parallel to the
magnetic field. We argue further that these instabilities heat predominantly the
electrons. We conclude that the efficiency of conversion of accretion energy to radiation
can be much smaller than unity only for the unlikely condition that the Ohmic heating of
the electron.
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