2025ApJ...995..138W -
Astrophys. J., 995, 138 (2025/December-3)
Magnetized Accretion Flows: The Key Roles of Viscosity and Black Hole Mass.
WU W.-B.
Abstract (from CDS):
In our previous work, we constructed a black hole accretion model incorporating magnetic fields and disk winds. However, this model was derived under conditions of a small viscosity parameter α (α < αcrit, where αcrit is the critical viscosity parameter) and for accretion systems around stellar-mass black holes. In the present study, we extend this model to regimes with α > αcrit and to supermassive black hole accretion systems. Our study reveals that under the condition of α > αcrit, the topological structure of thermal equilibrium solutions in black hole accretion disks undergoes significant changes. In the saturated state, the region dominated by advective cooling is confined to the inner disk, yet it expands radially as α increases. This may provide a theoretical explanation for the strong advection-dominated accretion flow (ADAF) principle, specifically addressing the connection problem between the standard thin disk (SSD) and ADAF. Furthermore, we find that the properties of the accretion disk depend on the mass of the central black hole. For stellar-mass black hole accretion systems, the optically thick radiative cooling solutions (similar to the SSD) remain stable, whereas for black holes with M ≥ 105M⊙, the optically thick radiative cooling solutions exhibit unstable behavior. These differences may help explain the distinct variability behaviors observed between X-ray binaries and active galactic nuclei.
Abstract Copyright:
© 2025. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
High energy astrophysics - Black holes - Magnetic fields - Accretion
Simbad objects:
9
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