Accretion disc

Assembled from 20 blocks · 2 evidence · 16 related

1. Story
2. The flattened, orbiting, inspiralling structure that forms when gas with angular momentum falls toward a compact object, and the source of essentially everything ever observed about black holes before 2015. Material cannot fall straight in: it must shed angular momentum first, and the mechanism is friction between adjacent annuli orbiting at different speeds. Shakura and Sunyaev parameterised that friction in 1973 with a single number, the alpha viscosity, without specifying its physical origin; the origin is now generally attributed to the magnetorotational instability, in which a weak magnetic field threading differentially rotating plasma becomes unstable and transports angular momentum outward. The disc heats as it drains, radiating from infrared to X-rays with the hottest material innermost, and terminates at the innermost stable circular orbit. Quasars are this process around supermassive holes; X-ray binaries are the same process around stellar-mass ones. Not a place on Earth.
3. Knowledge
4. Innermost stable circular orbit
5. Accretion disc
6. Connections
7. Innermost stable circular orbit
8. Relativistic jet
9. Cygnus X-1
10. Cygnus X-1 is localised and weighed
11. Bekenstein assigns entropy to a black hole
12. The first image of a black hole shadow is published
13. The M87* ring is imaged in polarised light
14. A second epoch shows the ring persists and the bright spot moves
15. The Kerr solution and black hole spin
16. Accretion disc
17. Kerr finds the rotating solution
18. Evidence
19. The standard thin accretion disc model, parameterising angular-momentum transport by a single viscosity coefficient. V55 VERIFICATION BASIS: not consulted in session; no research tool was available. Title, volume and page are from recall and must be checked.
20. Reports the first image of a black hole shadow, an asymmetric ring about 42 microarcseconds across, together with the array, observing campaign and imaging methodology. V55 VERIFICATION BASIS: not consulted in session; WebFetch to iopscience.iop.org and eventhorizontelescope.org was refused by the egress proxy and no search could be issued. Volume and article number are from recall of a canonical citation.