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BrobdingnagLilliput t1_j2oqs4d wrote

Reply to comment by Aseyhe in How do galaxies move? by modsarebrainstems

I thought galaxies existed because of supermassive blackholes and the nebulae we think of as "galaxies" are their accretion disks?

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Aseyhe t1_j2ot4uq wrote

Supermassive black holes form because of galaxies, not the reverse.

It has been suggested that supermassive black holes might form from "seed" primordial black holes, which would have existed before galaxies. But even then, it's the galaxy-scale initial density variations that allow galaxies to form around these seeds and grow them to supermassive scales.

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BrobdingnagLilliput t1_j2ovrhh wrote

Well, now my curiosity is piqued! I think I understand how ordinary black holes form as a result of stellar evolution, but can you point me to some decent resources on supermassive black hole formation? I'd prefer something closer to a book than a web page.

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StandardSudden1283 t1_j2pbegv wrote

What do you think about the idea that supermassive black holes at the center of galaxies were one the first generation of stars? Additionally, what do you think about black hole stars?

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deja_entend_u t1_j2qkfok wrote

Given the sheer SIZE of supermassive black holes and how quickly the formed post the big bang it seems there are great odds of SMBHs coming from some MEGA big stars that collapsed very quickly. Problem is to my knowledge we've never observed a star big enough to collapse INTO a supermassive black hole.

https://phys.org/news/2021-03-massive-stars-early-universe-progenitors.html#:~:text=The%20leading%20theory%20suggests%20the,into%20supermassive%20black%20holes%20today.

We would have to look back far enough to a now VERY distant galaxy to observe such a massive stars collapsing and merging. Hopefully JWST can confirm them!!

Regarding black hole stars: https://www.youtube.com/watch?v=aeWyp2vXxqA&t=609s

I think black hole stars could well be the origin of some of the supermassive black holes if a whole bunch could smash together!

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choicemeats t1_j2p4srj wrote

I just watched a video about the concept of black hole stars and the theory is honestly fascinating.

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charlesfire t1_j2pcutp wrote

Supermassive blackholes aren't nearly massive enough to hold together galaxies. If Sagittarius A* disappeared tomorrow, the Milky Way would be pretty much unaffected.

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purpleoctopuppy t1_j2ppxg6 wrote

Just to add some numbers, Sagittarius A* is 10⁶ solar masses while the Milky Way is 10¹², a million times more massive; comparable to the difference between the Earth and the Sun.

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Nayir1 t1_j2w3wrm wrote

Forget about accretion disks, that's a local phenomenon.You're right in the sense that galaxies exist because the Black hole at the center does not become massive enough to have all the matter. In the same sense that earth exists because of the sun because it the sun is not massive enough to have subsumed the earth. Also, nebulae are gas features within galaxies, but entire galaxies we're once called nebula before we realized they're just far away galaxies.

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