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: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".

The important question is How

[rossdee]

So how did the supermassive black holes get formed?

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."

Both?

[fygment]

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

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: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