What Came First, Black Holes Or Galaxies?

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."

Comments

Answer

[Anonymous Coward]

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

[Anonymous Coward]

medium.com unreadable fluff. Please find a better website to spam. Not all of us have tablets, you know.

Re:To form supermassive blackholes

[invictusvoyd]

http://en.wikipedia.org/wiki/R... -- 265 solar masses

Uuh, wrong question

[Rosco P. Coltrane]

I read somewhere that the heavens and the Earth came first.

Re:Uuh, wrong question

[Livius]

What do you think the heavens are made of? Obviously all the parts of the heavens came first.

Re:Uuh, wrong question

[rtb61]

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...

[bayankaran]

Not black holes, nor galaxies, but da chicken came first.

Re:To form supermassive blackholes

[Gaygirlie]

Well, you replied to yourself with that link. If you'd read the page you'd notice the link to http://en.wikipedia.org/wiki/R... which is a galaxy with several supermassive stars.

Re:To form supermassive blackholes

[Anonymous Coward]

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:Duh!

[Anonymous Coward]

Chuck Norris came 0th. Not first.

The important question is How

[rossdee]

So how did the supermassive black holes get formed?

Re:The important question is How

[stonedead]

This. Observed black holes have so far been either 1) Stellar - tens or may be hundreds of solar mass or 2) Supermassive - millions to billions of solar mass. We haven't seen anything in between. So with the data at hand, the question is: Are Supermassive are formed from big bang or they are "formed" as they pull heavenly bodies towards them?

Re: The important question is How

[Anonymous Coward]

Black holes are at least consistent with general relativity which is heavily tested in other regimes, and do not require assumption of other exotic materials and processes that lack other related observations. Direct observation of the stars moving through the area show whatever is there has a mass of millions times that of the Sun, but must be smaller than Saturn's orbit (otherwise the passing stars would have hit it). Other radio, x-ray, and gamma ray observations are consistent with a black hole accretion disk and structure of someone thing yet even smaller than that. The only vanilla physics based alternatives are that we were really lucky to see something right before it became a black hole, because despite the billions of years the galaxy has been around, we caught it when stuff was falling together that would take a tiny fraction of that to form a black hole anyway. Otherwise, even more esoteric proposals involve theories without other observations. To treat those all as equal is the same as saying, "it could just a likely be there are a lot of angels there pushing on things harder."

what if

[cellocgw]

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

[Esra Erimez]

Is this not too dissimilar to how we think the solar system started, the sun first and then the planets?

Both?

[fygment]

Why is the answer always assumed to be binary? Both processes could have been occuring simultaneously.

Re:Both?

[mbone]

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.

Re:Both?

[mbone]

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.

Re:Both?

[mick129]

From The Fascinating Article:

In other words, both the top-down and the bottom-up scenarios play a role, but the bottom-up, by virtue of starting smaller, gets a head start by millions of years!

The answer is not assumed to be binary.

Speaking of why Medium.com sucks

[Anonymous Coward]

Speaking of why Medium.com sucks...

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?

Evading the question

[Livius]

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

[mbone]

we first expected and then found supermassive black holes at the centers of practically all large galaxies.

"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. Before all of this most astronomers weren't interested in black holes and even the small number of General Relativity types (such as Zeldovich) who were, and who were looking them, were looking for stellar mass sized black holes, not the SMB variety.

All in all, I think it would be more accurate to say that the SMB-galaxy connection was forced upon astronomers by the data, rather than that they expected it.

SMB formation theory is uncertain

[mbone]

Having read the article, I think that "With a Bang" sort of waffled on this. It is hard to see 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, might be interesting to people interested in these problems, but it deals with the galaxy problem more than the SMB problem.

Re:SMB formation theory is uncertain

[Rich0]

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 gradients that just sucked gobs of matter into SMBs and arranged the larger area around it into galaxies. Those forces may no longer be active today, and they may very well have only been active for a short time to have a big impact on large-scale structures.

However, what I don't know is how something like this would affect the CMB/etc, and this sort of thing may have been completely disproven.

Re:To form supermassive blackholes

[Almost-Retired]

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

What came first?

[IsoQuantic]

God.

Why do ACs think they're smarter than Einstein?

[Tenebrousedge]

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 threshold. Whether or not singularities exist in some sort of real way is another question. The internal structure of black holes is also fairly academic. That black holes exist is, as has been said, a direct consequence of General Relativity, which has been shown to be an extremely accurate description of the geometry of the universe, at all scales we have been able to observe, from the sub-atomic to the intergalactic. In order for black holes (or a phenomenon with identical properties) not to exist, you have to both explain the observation of these dense, massive objects, and simultaneously describe why objects cannot be that dense, or more precisely why spacetime cannot be curved such that it forms an event horizon.

ACs: if you do not have a working knowledge of relativity then please don't trouble yourselves to respond to this comment. Your theory has to have greater explanatory power if you want to replace relativity, and if you don't know what it says, well, you're not likely to have a useful opinion on the matter.