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posted by cmn32480 on Sunday September 03 2017, @03:16PM   Printer-friendly
from the star-gravestones dept.

Arthur T Knackerbracket has found the following story:

UCLA physicists have proposed new theories for how the universe's first black holes might have formed and the role they might play in the production of heavy elements such as gold, platinum and uranium.

Two papers on their work were published in the journal Physical Review Letters.

A long-standing question in astrophysics is whether the universe's very first black holes came into existence less than a second after the Big Bang or whether they formed only millions of years later during the deaths of the earliest stars.

Alexander Kusenko, a UCLA professor of physics, and Eric Cotner, a UCLA graduate student, developed a compellingly simple new theory suggesting that black holes could have formed very shortly after the Big Bang, long before stars began to shine. Astronomers have previously suggested that these so-called primordial black holes could account for all or some of the universe's mysterious dark matter and that they might have seeded the formation of supermassive black holes that exist at the centers of galaxies. The new theory proposes that primordial black holes might help create many of the heavier elements found in nature.

The researchers began by considering that a uniform field of energy pervaded the universe shortly after the Big Bang. Scientists expect that such fields existed in the distant past. After the universe rapidly expanded, this energy field would have separated into clumps. Gravity would cause these clumps to attract one another and merge together. The UCLA researchers proposed that some small fraction of these growing clumps became dense enough to become black holes.

Their hypothesis is fairly generic, Kusenko said, and it doesn't rely on what he called the "unlikely coincidences" that underpin other theories explaining primordial black holes.

The paper suggests that it's possible to search for these primordial black holes using astronomical observations. One method involves measuring the very tiny changes in a star's brightness that result from the gravitational effects of a primordial black hole passing between Earth and that star. Earlier this year, U.S. and Japanese astronomers published a paper on their discovery of one star in a nearby galaxy that brightened and dimmed precisely as if a primordial black hole was passing in front of it.


Original Submission

 
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  • (Score: 0) by Anonymous Coward on Sunday September 03 2017, @05:39PM (4 children)

    by Anonymous Coward on Sunday September 03 2017, @05:39PM (#563190)

    No, dark matter can't be black holes. See figure 2 here:

    If one interprets the left hand side of Eq. (3) as a measure of the dark matter (which is the interpretation given to it in the standard model), the right hand side implies that the dark matter distribution is strictly tied to that of the normal matter, and furthermore that the relation is a simple algebraic one.

    http://www.sciencedirect.com/science/article/pii/S1355219816301563 [sciencedirect.com]

    No one has ever supposed black holes would act like that (be present in just the right ratio with visible matter).

  • (Score: 0) by Anonymous Coward on Sunday September 03 2017, @07:50PM (3 children)

    by Anonymous Coward on Sunday September 03 2017, @07:50PM (#563212)

    That's a philosophy paper, not a science paper.

    • (Score: 1, Touché) by Anonymous Coward on Sunday September 03 2017, @10:11PM (2 children)

      by Anonymous Coward on Sunday September 03 2017, @10:11PM (#563238)

      It's a review article, be careful about following heuristics off a cliff. Knowing when to apply various heuristics or not is basically the definition of intelligence. Anyway, :https://doi.org/10.1086/421338

      • (Score: 0) by Anonymous Coward on Monday September 04 2017, @05:38AM (1 child)

        by Anonymous Coward on Monday September 04 2017, @05:38AM (#563300)

        Well, at least this irrelevant paper is about dark matter. But it has little to say on the subject of what form dark matter might take (other than that the author seems to prefer MOND, but MOND is not plausible today as it was in 2003).
        https://www.xkcd.com/1758/ [xkcd.com]

        Nothing in this paper would exclude primordial or microscopic black holes. While black holes aren't technically baryonic matter, nothing prevents them from being found in the same regions of space. Most dark matter candidates today are not baryonic matter, as MACHOs are out of favor.

        • (Score: 0) by Anonymous Coward on Monday September 04 2017, @03:02PM

          by Anonymous Coward on Monday September 04 2017, @03:02PM (#563468)

          As originally noted, why is there a constant ratio of visible to black holes? You haven't offered any explanation for this and it is very strange (if dark matter is black holes) that many galaxies of different ages would have the same relationship.