Two-dimensional structure of thin transonic discs: theory and observational manifestations

Abstract

We study the two-dimensional structure of thin transonic accretion discs in the vicinity of black holes. We use the hydrodynamical version of the Grad-Shafranov equation and focus on the region inside the marginally stable orbit. We show that all components of the dynamical force in the disc become significant near the sonic surface and especially important in the supersonic region. Under certain conditions, the disc structure is shown to be far from radial, and we review the affected disc properties, in particular the role of the critical condition at the sonic surface: it determines neither the accretion rate nor the angular momentum in the accretion disc. Finally, we present a simple model explaining quasi-periodical oscillations that have been observed in the infrared and X-ray radiation of the Galactic Centre.

Accepted to A&A; 11 pages, 7 figures, uses aa.cls

References in corpus (5)

• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• Magnetically Driven Accretion Flows in the Kerr Metric I: Models and Overall Structure
• Black Hole Spin Evolution
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• Effective sound speed in relativistic accretion discs around Schwarzschild black holes
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• Carter-Penrose diagrams for emergent spacetime in axisymmetrically accreting black hole systems
• Influence of matter geometry on shocked flows-I: Accretion in the Schwarzschild metric
• The thickness of a weakly-magnetized accretion flow inside the last stable orbit of a Kerr black hole
• Transonic behaviour and stability analysis of quasi-viscous black hole accretion