Spectral Models of Advection‐dominated Accretion Flows with Winds

Abstract

We calculate spectral models of advection-dominated accretion flows, taking into account the possibility that significant mass may be lost to an outflow/wind We apply the models to the soft X-ray transient V404 Cyg in quiescence, the Galactic center source Sgr A*, and the nucleus of NGC 4649. We show that there are qualitative degeneracies between the mass-loss rate in the wind and parameters characterizing the microphysics of the accretion flow; of particular importance is delta, the fraction of the turbulent energy which heats the electrons. For small delta, current observations suggest that at most 90% of the mass originating at large radii is lost to a wind, so that at least similar to 10% reaches the central object. For large delta similar to 0.3, however, models with significantly more mass loss are in agreement with the observations. We conclude by highlighting future observations which may clarify the importance of mass loss in sub-Eddington accretion flows.