3 ms·

OK, so this is less than 1% the size of supermassive black holes: > Weighing in at about 50,000 times the mass of our Sun, the black hole is smaller than the s

OK, so this is less than 1% the size of supermassive black holes: > Weighing in at about 50,000 times the mass of our Sun, the black hole is smaller than the supermassive black holes (at millions or billions of solar masses) that lie at the cores of large galaxies, but larger than stellar-mass black holes formed by the collapse of a massive star. And then about this question ... > Does a supermassive black hole grow from an IMBH? It'd take at least hundreds of mergers to get even small supermassive black holes. So does that mean that mergers mainly occurred when stuff was closer together?

goodcanadian 7y ago
I would say where stuff is closer together rather than when although I'm sure there is an element of when involved, also. Supermassive black holes are found at the centre of galaxies where there is a much higher density of matter to begin with.
- mirimir 7y ago
  I was thinking when as in before or during inflation. But maybe that's silly.
sandgiant 7y ago
Yes, mergers were more common at earlier times. But in fact, even with mergers, it's exceedingly difficult to get supermassive black holes to merge in the first place. Because they are tiny compared to the sizes of the galaxies they inhabit, they have to somehow be pushed close enough that they start orbiting each other and radiate away orbital energy in the form of gravitational waves. Only then can they hope to merge into a single black hole. It's actually so difficult that one popular explanation for the existence of supermassive black holes is that they are the peaks of the primordial density perturbations that collapsed into supermassive black holes in the very early universe. See https://en.wikipedia.org/wiki/Primordial_black_hole https://en.wikipedia.org/wiki/Primordial_black_hole
- mirimir 7y ago
  Thanks. Merging did seem improbable. I do recall the hypothesis about primordial density perturbations. There's a great animation about that in Takashi Miike's God's Puzzle.

goodcanadian 7y ago

I would say where stuff is closer together rather than when although I'm sure there is an element of when involved, also. Supermassive black holes are found at the centre of galaxies where there is a much higher density of matter to begin with.

mirimir 7y ago
I was thinking when as in before or during inflation. But maybe that's silly.

sandgiant 7y ago

Yes, mergers were more common at earlier times. But in fact, even with mergers, it's exceedingly difficult to get supermassive black holes to merge in the first place. Because they are tiny compared to the sizes of the galaxies they inhabit, they have to somehow be pushed close enough that they start orbiting each other and radiate away orbital energy in the form of gravitational waves. Only then can they hope to merge into a single black hole. It's actually so difficult that one popular explanation for the existence of supermassive black holes is that they are the peaks of the primordial density perturbations that collapsed into supermassive black holes in the very early universe. See https://en.wikipedia.org/wiki/Primordial_black_hole https://en.wikipedia.org/wiki/Primordial_black_hole

mirimir 7y ago
Thanks. Merging did seem improbable. I do recall the hypothesis about primordial density perturbations. There's a great animation about that in Takashi Miike's God's Puzzle.