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Abstract: We briefly review recent developments in black hole accretion disk theory,placing new emphasis on the vital role played by magnetohydrodynamic MHDstresses in transporting angular momentum. The apparent universality ofaccretion-related outflow phenomena is a strong indicator that verticaltransport of angular momentum by large-scale MHD torques is important and mayeven dominate radial transport by small-scale MHD turbulence. This leads to anenhanced overall rate of angular momentum transport and allows accretion ofmatter to proceed at an interesting rate. Furthermore, we argue that whenvertical transport is important, the radial structure of the accretion disk ismodified and this affects the disk emission spectrum. We present a simple modeldemonstrating that energetic, magnetically-driven outflows give rise to a diskspectrum that is dimmer and redder than a standard accretion disk accreting atthe same rate. We briefly discuss the implications of this key result foraccreting black holes in different astrophysical systems.



Autor: Zdenka Kuncic USyd, Geoffrey V. Bicknell ANU

Fuente: https://arxiv.org/







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