Observed galaxies in the cosmos nearly all contain a supermassive black hole. These SBH’s have masses closely tied in the hosting galaxy size, suggesting a strong correlation in formative history. Our galaxy’s SBH has a mass of over 3 million solar masses, crammed in to a region smaller than the orbit of Mercury around the sun, and the biggest galaxies can generate SBH’s up to several tens of billions of solar masses – our universe is not capable of producing bigger ones. These biggest ones have gargantuan event horizons, and we can safely assume anything orbiting closer than several hundred times the event horizon will be torn by tidal effects. In case of the theoretically biggest SBH at 50 billion solar masses this comes down to 1.4755948039186453 x10E14 meters. That is significantly bigger than the current solar system, including the outermost KBO objects. At those sizes stars can just fall in without generating an accretion disk. If they fall in at a very steep angle they might even survive as stars (with planetary systems included) until just at the edge of the event horizon, having been accelerated up to very close the speed of light.
This opens up an interesting vista, stemming back from the concept of kessler syndrome. This is a theory that stipulates that artificial satellites in orbit around Earth might start crashing, producing debris, and respective debris continuing to pulverize satellites until there is little left than debris. We have seen a similarly phenomenon with Saturn, and there’s a pretty good SF novel that explores the same mechanism to its most terrifying conclusion. In comparison with its rings Saturn is very big. Apparently in the universe there are planets with much bigger ring systems. It stands to reason to label these “dormant” accretion disks. Gradually some ring material will collide and degrade in respective orbits, but ring systems may theoretically last a long time. Saturns rings are estimated to last millions to billions of years.
With black holes the rings can move ‘very close’ to the black hole, to the point that shear and frame drag will produce friction/radiative heat, theoretically much hotter than the inside of a star. Such heat produces fusion. This radiation pressure will generate a push to orbiting ring material, evaporating some of this material and thrusting it outward with much the same mechanical effect as a sun generating clouds. If this ablated material is, say, iron, the material may move in discrete clouds pushed by radiation pressure from the black hole outward over and under the rings and rain down back on to the rings at a point where the emitted heat of the black hole drops below the heat required to keep the ablated material in a gaseous state.
As I quoted in a previous article, black holes are likely to come with intricate shapes, depending on the direction of rotation of the black hole versus angular momentum of the infalling material. But whatever the case these rings build up in cycles and I am pretty certain outer rings can last a long, long time. Inner rings will ablate because of occasional bursts of radiation (although I argue this ablation may re-condense outward in the system) and frame dragging and torque.
I just heard that the number of stellar remnants, in particular black holes, white dwarfs and neutron stars (et.al. – there will almost certainly be stellar artfacts there we haven’t even imagined yet with contemporary science), numbering in the many tens of thousands will be orbiting the region around Sagittarius A* in a proximity of mere light years. When I heard this I exclaimed something along the lines of holy shit.
To keep a TL;DR as short as possible, this will produce Kessler effect. The presence of a swarm of very dense objects produces a maelstrom of tidal torque. The violence of tidas will produce swarms of continuously infalling material, until all material in the area is stripped clean. The result will be a very big, very dark, very long lasting ring system around Sagittarius A*. There is likely to be some star formation in this ring system (shepherd stars? Shepherd black holes?) but I’ll assume these shepherding objects to not expand beyond the size of brown dwarfs. In fact I can imagine there to be white dwarfs accumulating material close to this singular ring system and exploding in respective type 1a supernovae intermittently.
Since I am not a professional astrophysicist I’d love to hear what the insiders think of this analysis.