[FRIAM] primordial or primeval?

[David Eric Smith]

What a great shot in the arm to start a morning.

I just got back from a small conference in Groningen, which turns out to be (I didn’t know) a kind of fountainhead for large-scale structure cosmologists.  So got some much-needed remedial education on the topics in Glen’s links below.

I asked one guy what was the bound on how many black holes could have been produced early, given what we know today, thinking (in my near-total ignorance) that it would be collisions reported with the LIGO et al. collaboration.  His answer mentioned something I didn’t see in these articles, which was that microlensing counts are likely to provide some of the best bounds on the primordial black holes if they are to be dark matter candidates.  This is when a telescope is looking at some distant dim dot, and it briefly flickers brighter because a black hole passed between it and us, and lensed in a tiny bit more angular sector of its light.  I guess Webb contributes to those counts too (if I didn’t create a further mis-understanding).

The idea that all of dark matter could be accounted for with nothing but black holes is strangely both tempting and disappointing.  Tempting in that, in the short term, it would explain a phenomenon, and check one more off the list.  Disappointing in that, if we could close _everything_ we can observe with just the low-energy standard model and general relativity, then we have no clues what to do to make them consistent.  If there were at least some phenomena that we could show were _sure_ to be beyond explanation with the existing models, we could at least hang a hope on there's being some signature to lead into this very deep high-energy wilderness that, for now and maybe indefinitely, we can’t reach in any lab on Earth.

Good stuff,

Eric



> On Jun 27, 2022, at 11:39 PM, glen <gepropella at gmail.com> wrote:
> 
> I'm guessing "primordial" carries the foundationalist urge, whereas "primeval" is more agnostic to foundations, but targets sequence. So the test for hypothesis is simply *if* Webb finds no evidence of small black holes, then the they can't account for dark matter. Right? Or is there something more subtle about it? ... mabye something "distributional"?
> 
> Black holes and dark matter — are they one and the same?
> https://news.yale.edu/2021/12/16/black-holes-and-dark-matter-are-they-one-and-same
> 
> Webb’s Quest for Primeval Black Holes
> https://blogs.nasa.gov/webb/2022/05/26/webbs-quest-for-primeval-black-holes/
> 
> And maybe tangentially,
> 
> Astronomers identify likely location of medium-sized black holes
> https://phys.org/news/2022-04-astronomers-medium-sized-black-holes.html
> 
> P.S. July 12th:
> First Images of the James Webb Space Telescope (Official NASA Broadcast)
> https://youtu.be/nmMRMIE3MGw
> 
> -- 
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