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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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What Came First, Black Holes Or Galaxies?

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  • Answer (Score:4, Informative)

    by Anonymous Coward on Saturday July 05, 2014 @04:48AM (#47387335)

    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.

  • by Anonymous Coward on Saturday July 05, 2014 @05:29PM (#47390039)
    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."

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