Ein massereiches Schwarzes Loch hat so viel Masse der umgebenden Galaxie verschluckt, dass es in einen Ruhezustand übergegangen ist

Good for him! I know some people that just *can’t* stop eating!

Eli5 what does it mean for a black hole to be “dormant”? It’s still gonna have the same gravity right? It can’t have a flare up and go back down again can it?

By chance did this happen on the third Thursday of November? 

That’s not going to be a pleasant next trip to the bathroom

Astronomer here! This is just about the worst summary of a summary ever- for those who want to know what’s really going on, [here](https://phys.org/news/2024-12-dormant-massive-black-hole-early.html) is a better article and [here](https://arxiv.org/abs/2403.03872) is the paper itself.

The black hole in question is actually very far away from us- so far that we see it at the dawn of the universe, when the universe was just 800 million years old (as opposed to the ~13.8 billion years old it is today). It was discovered by a JWST survey looking at the earliest galaxies, and is on the more massive side for sure- 400 million times the mass of the sun! (For the record, our own supermassive black hole in our galaxy, Sagittarius A*, is about 1% of that.) What’s more, you can tell how much black holes are accreting (aka, growing by having gas fall onto them), and the black hole has such a low limit of accretion that it’s effectively not accreting any more material. What’s more, the galaxy itself isn’t forming many stars at all- about 1 new Sun a year, which is 3x lower than what most galaxies do at that period of time.

So, it’s very complicated to theoretically explain how you get such a ginormous black hole so early in the universe, and we have a black hole no longer accreting in a galaxy without much star forming going on. So far as we can tell, this means the black hole effectively has *already* swallowed most of the available material around it, and has gone dormant. This is an unusual find because, as I’m sure you can imagine, it’s usually *really* hard to detect black holes that are very far away that aren’t accreting material because, well, they’re black and don’t emit anything unless there’s material interacting near their event horizon. And JWST data is new enough that if you find one of these guys, it implies there’s probably a population of very supermassive black holes out there in the universe that we just can’t easily probe! How many? Well, that’s something you need to find more of to find for sure, and it’ll be interesting to see what we end up finding!

Finally, this also has potential implications for how supermassive black holes form- is it from sucking in material and merging with other black holes, or were they “seeded” in over-dense fluctuations in the earliest moments after the Big Bang? Theory definitely favors the former over the latter, but it definitely appears from JWST data that black holes formed and got bigger MUCH faster than a lot of theories predicted before we actually had data at hand. So a discovery like this is super useful for studying those formation channels.