What Came First, Black Holes Or Galaxies? 76
StartsWithABang (3485481) writes "It was one of the most hotly contested questions for decades: we first expected and then found supermassive black holes at the centers of practically all large galaxies. But how did they get there? In particular, you could imagine it happening either way: either there was this top-down scenario, where large-scale structures formed first and fragmented into galaxies, forming black holes at their centers afterwards, or a bottom-up scenario, where small-scale structures dominate at the beginning, and larger ones only form later from the merger of these earlier, little ones. As it turns out, both of these play a role in our Universe, but as far as the question of what came first, black holes or galaxies, only one answer is right."
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Chuck Norris came 0th. Not first.
Answer (Score:4, Informative)
So the best answer we have is that the seeds of supermassive black holes and the seeds of galaxies were what formed first, and they did so at approximately the same time. But these black holes began as quite large structures, growing to at least many thousands of solar masses before the environments in which they were housed could ever be considered galaxies, and so it appears that black holes came first, but they form in regions that will merge-and-grow into large, rich galaxies in very short order.
The article has a pretty in-depth explanation (from what my layman's eyes can see) though.
Bah (Score:2, Insightful)
medium.com unreadable fluff. Please find a better website to spam. Not all of us have tablets, you know.
Speaking of why Medium.com sucks (Score:1)
Why do stories on sites like Medium.com scroll so badly? Jerky, screen tearing...who would want this?
Personally, I avoid sites like this. It is a trivial matter to type some of the article text into Google and find a different web site.
But back to my question...Is it because of the mega large graphics/background? Can I just block that in some way? In Opera?
To form supermassive blackholes (Score:1)
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To form supermassive blackholes There need to be supermassive stars
Non sequitur. A supermassive black hole can form by the merger of smaller black holes, normal stars, interstellar gas, even dark matter. The only snag is that these things need to get close to each other, because - contrary to popular belief - black holes don't "suck".
Re:To form supermassive blackholes (Score:4)
Not in the short haul because the mass that creates the gravity well usually stays within that galaxy. Long haul, as in several trillion years, the two black holes will orbit as before when they both were just stars, but the gravitational waves they emit is a loss of system energy and they will slowly spiral into each other until they merge. But that may take longer for most of them than the universe is old. We are actively looking for the gravity wave that would indicate two such black holes have merged as it will have a distinct waveform.
Cheers, Gene
Uuh, wrong question (Score:5, Funny)
I read somewhere that the heavens and the Earth came first.
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What do you think the heavens are made of? Obviously all the parts of the heavens came first.
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The multi-verse. From chaos, every thing, every where, every when, life enforced a singular time line, some thing, some where, some when because you can never have nothing, no where, no when. Although not to be fooled, time as such doesn't exist, it is just a life based relative measure of change.
Neither... (Score:2, Insightful)
The important question is How (Score:3)
So how did the supermassive black holes get formed?
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Why do ACs think they're smarter than Einstein? (Score:2)
What brought out the cranks today?
Anyone who can claim that General Relativity is wrong has not understood it. It is incomplete, but it is not wrong, and certainly not to the point where black holes would be 'disallowed'. We're pretty good so far at determining what fundamental forces operate in the universe, and there simply is no property of matter which would prevent it from reaching the densities required for black hole formation. We have observed extremely massive dense objects far exceeding that thres
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what if (Score:2)
But what if a galaxy formed, then after a few billion years collapsed entirely into the central black hole, which then caused a new galaxy,...
(leading vaguely to a Yo Dawg meme here)
Solar system (Score:1)
Both? (Score:5, Interesting)
Why is the answer always assumed to be binary? Both processes could have been occuring simultaneously.
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Why is the answer always assumed to be binary? Both processes could have been occuring simultaneously.
I am sure both were occuring simultaneously, the question is, which dominates? The two sets of processes have different time constants (growth rates), arising from different physics. For both to be more-or-less equally powerful requires these time constants to be more-or-less matched, and that seems improbable and fails "Occam's razor" type "tests."
So, could be, but don't expect that idea to gain traction, at least without a good theory as to why things should be that way.
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Of course, as the "With a Bang" article points out, if you are willing to wait and not have everything be simultaneous, you can have both large scale structure formation and small scale structure formation going on simultaneously, with the small scale going to completion earlier, and both together yielding what we see today.
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The answer is not assumed to be binary.
Evading the question (Score:2)
Of course black holes.
Then galaxies.
But super-massive black holes - the interesting question - probably came last, although they avoided that aspect of the question.
SMB were a surprise (Score:2)
"expected" is sure not how I remember it, and in fact I think this has the historical record backwards. Quasars were definitely a surprise, and the Super Massive Black hole (SMB) interpretation of quasars took a while (a decade at least) to catch on, and the consensus that most galaxies have a central SMB came after that, after some local galaxies (such as our own) showed signs of having a SMB too. Be
SMB formation theory is uncertain (Score:3)
Having read the article, I think that "With a Bang" sort of waffled on this. It is hard to see [arxiv.org] how SuperMassive Black holes (SMB) form in the time available for them to form. (There is a large literature on this, but basically there are problems of the seeds - are the seeds Pop III stars, or something more exotic - and time - how can the mass move around enough to form SMB by z ~ 6?).
I don't really feel you can safely answer the "which came first" question until you know how the SMB actually formed.
A one hour video lecture, Supermassive Black Holes and the Problem of Galaxy Formation [youtube.com], might be interesting to people interested in these problems, but it deals with the galaxy problem more than the SMB problem.
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Thanks for the link - haven't watched it yet.
I've always wondered if Galaxies and SMB are both effects from a common cause. We don't understand dark matter, and that is a HUGE gap when it comes to galaxy formation. If there is some kind of primordial force at work that created the large-scale structure of the universe then perhaps SMB are just an extreme manifestation of it. They didn't necessarily form from steller evolution. Maybe at some period in the past if not today there were huge gravitational g
What came first? (Score:1)
God.