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First Stars - How big - Now Black Holes?

  1. Mar 17, 2005 #1
    First star-forming gas clouds were much denser. (Early Universe was smaller and prior to stellar fusion also had more hydrogen.) Did not most first generation stars leave Black Holes behind when the rapidly completed their life cycle? How much did the universe expanded while the first stars ran their life cycle and typically formed a pair of gravitationaly bound black holes? Did the typical star pair of the second generation also leave a pair of black holes behind when it died? How many generations before the typical star did not leave a black hole behind? How does the number of these early-generation stellar-core black holes compare with the total number of currently luminious stars? Are there enough black holes to account for "dark matter"? I.e. what fraction of the matter that "condensed" from Big Bang energy is now in black holes?
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  3. Mar 17, 2005 #2


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    A lot of different questions, but all actually tied into one subject of "first stars". Good question(s) too.. :tongue2:

    I think that a review of the following sites would probably answer all questions at least to some degree. I think that I posted at least one of these before on another thread, but they are all related.






    Let me know if there is still a specific question left... :yuck:

    EDIT: This one is short but has good info:
    Last edited: Mar 17, 2005
  4. Mar 17, 2005 #3


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    A time ago I read a paper about black hole remnants of population III stars with Joseph Silk as coauthor, but now I was unable to find the reference again. If I recall correctly, it was postulated that most of these black holes merged hierarchically to form the supermassive black holes in the present galaxies. (I don't know whether this is the accepted view; for me it was new and I found it very interesting).

    [Edit] I found the reference:
    Massive black hole remnants of the first stars I: abundance in present-day galactic haloes
    Last edited: Mar 17, 2005
  5. Mar 17, 2005 #4
    Thanks for ref. I looked at them all. Have saved the two best here. Your first was usless for me.

    I now understand the importance of "metals" - the presence of bound electrons makes for both rapid radiation and absorption of photons, probably harse UV /soft X-rays. This permits some of the thermal energy to leave (cool) metal containing gas clouds and should also make for greater temperature uniformity. Thus, smaller post generation III stars can form as the gas is less hot and does not require so much to self gravitate / collapse.

    I would not however expect uniform density within the gas cloud or for it increase steadly towards a single interior point. Thus I expect at least two regions within the cloud will eat up most of the others and form a pair of stars. The references you gave seem to be describing isolated stars. Perhaps the pairs are so far apart that they do not interact much in the evolution of each; however if all the original angular momentun must be preserved in one star - it seem to me that it could not collapse and heat to fusion temperatures. Also it seems at least poossible the gas cloud could have many condensation centers built on many very small black holes - see next paragraph.

    What happened to magnetic monoploes that should have formed? Is my idea that they did, an N one being attracted to an S one and them fusing to form a micro black hole crazy? I have read that one alone might be come a BH because they are so much heavier than protons (10^15 to 10^22 times heaver as I recall reading.) If this is possible, could not these micro BHs pay an important role in condensing gas to start a star up? Nonthing about this in your references. If they do but "evaporate" does this not provide radiation to keep thing ionized (no molecular hydrogen cooling etc?) Would the extremely red shifted remanents of this radiation be seen to day? (like the cosmic background 4 degree radiation) What temperature should it have?

    Any idea why the dark matter is thought to separate from baryon/ electron matter? Does not make sense to me. - gravity is gravity is it not? The more I read, the less I know.

    Thanks - what do you think of these concerns?
  6. Mar 17, 2005 #5


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    Pretty charts, though.. :smile:

    I can't disagree with any of this part. Not that I know, I'm just not aware of any info to the contrary.

    For smaller-than-galactic scales I think that you, and some of S.E. Woosley's papers, are correct in this and that large clouds that can retain their angular momentum do, in fact, "fracture into two stars and the pair cannot be seperated by ous instruments. This is exactly what Woosley is assuming for the Pistol star that I posted somewhere in the last day or so.

    The angular momentum doesn't need to be preserved, and probably can't. See:


    where part (pg.2) states that:
    That's a pretty good paper and also points out (pg. 2 also):
    And, on pg. 5:
    Page 3 also starts the effect of magnetic fields. It's only 6 pages but a good one, I think.

    As far as I know, magnetic monoploes can be predicted but have never been detected, Haven't read enough on that to comment. As far as the micro black holes, I'm only aware of those that could have been caused at the BB but would be too short-lived and too small to effect Population III and galactic BH formation significantly. As far as the (2.73K) IRB, the role of massive stars/black holes is discussed at(excellent paper):


    All I can say is that so little is known (yet) about dark matter that I wouldn't know why it would be affected by gravity any differently. In fact, gravitational effects were how it was first discovered!
  7. Mar 18, 2005 #6


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    They sepparate because ordinary barionic matter collapses due to electromagnetic interactions which lead to loss of energy. Non-barionic matter interacts only gravitationally.
  8. Mar 18, 2005 #7
    yes pretty, but about as informative to a non professional as flowers, which are also pretty.
    Only skimmmed this ref. I understand that sub galactic regions might interact, if not in actual collisions, via magnetic torques, and tend to reduce their initially larger "local eddy" angular momentum, but even still I suspect that most will still find it easier to from a pair of stars rather than one.
    Before reading your ref, a "crazy idea" for shedding angular momentum occured to me, and it seems reasonable the more I think about it.
    Consider a local eddy of pre-stellar gas still cold enough to have some molecular hydrogen (or post generation III with metals) for efficient radiation. If a photon (line radiation) is emitted in the direction of spin, it will have slightly higher frequency (externally measured) than when emitted in the opposite direction. The momentum it carries away is thus slightly larger. How significant is the "breaking mechanism"?

    I am going to reply to helfire's comments on my problem with the separation of dark and regular matter - please read and comment also.
  9. Mar 18, 2005 #8
    This explains why the regular matter is cooler, not why they separate. In one of Lab guy's references I read that it is thought that the (hotter - I assume) dark matter formed "walls" etc. If anything did so, I would think it would be the colder regular matter, but even then, why does not the dark matter congregate around the condensing regular matter? What am i missing here?
  10. Mar 18, 2005 #9


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    I think cooling it explains the sepparation. The collapse and fragmentation of gas requires energy dissipation. If matter cools, then it looses energy and the orbits will became closer. Thus, the isothermal collapse which leads to a decrease of the Jeans' mass and to a successive fragmentation of a cloud until cooling does not take place, is only possible with baryonic matter. On the contrary, a swarm of non-baryonic particles will never fragmentate into smaller parts; the orbits will be modified due to gravitational interaction, but neither collapse nor fragmentation will take place.
  11. Mar 18, 2005 #10
    But as i understand it it is the hotter dark matter that is susposed to have condensed and separated. This is waht is confusing me. For example, from Lab guy's third ref (post 2) I read:

    "Although dark matter is thought to be relatively segregated from ordinary baryonic matter in outer galactic halos and intergalactic space today, the two may have been mixed initially. As the dark matter condensed into a denser filamentary network, ordinary matter made of hydrogen and helium gas also was gravitationally attracted by these relative concentrations of dark matter, creating Lyman-alpha "forest" clouds of gas. At the nodes of the dark matter filaments, these gas clouds collapsed under gravitation towards of the cores of denser clumps of 100,000 to one million Solar-masses that may have measured around 30 to 100 light-years across and still consisted mostly of dark matter."

    What you are explaining to me would be easy to accept if the standard theory were the other way round - I.e. if the cooling of ordinary matter permitted it to condense and then attract the dark matter to the denser aggregates of ordinary matter, but that does not seem to b what the experts are saying happened. See my confusion? :grumpy:
  12. Mar 18, 2005 #11


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    Correct, but what you are describing happens much farther away in past. At the time before of recombination, at redshifts z > 1100, the baryons are strongly coupled to photons, which generate a radiation pressure keeping baryons from collapsing. As dark matter interacts only gravitationally, its density fluctuations may grow at that time as well as earlier. So, well, you could call this growth of fluctuations "collapse of dark matter", but note that the process is very different than in the baryonic case, as it is only driven by gravitation. After recombination, radiation and baryonic matter decouple and the baryons will fall into the gravitational potentials created by dark matter. This is the typical "collapse", which is described in the theory of gravitational instability. This infall into preexisting dark matter potentials is actually necessary in order to explain structure formation, since otherwise there would not be enough time for the baryonic fluctuations to develop after recombination.
    Last edited: Mar 18, 2005
  13. Mar 19, 2005 #12


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    Billy, why are you asking these questions? You obviously know the answers to most of them. I find that annoying. hellfire, whom I hold in high regard, is trying to answer them, but, you seem more inclined to argue.
    Last edited: Mar 19, 2005
  14. Mar 20, 2005 #13
    It is true that I know something about black holes and early universe, but not nearly as much as several others - For example until a few days ago, I was assuming that the first generation of stars were called generation I and that generation III would be the third. Some things I "know" are not well accepted and I want to understand why (change my view if need be etc.) For example, Hawking radiation, I understand well that small BHs have a much stronger gradient just outside their event horizon and assume this helps them swallow only one member of the vacuum polarization pair (leaving the other stable in our universe - at least for a while, much longer than the uncertainty product between E and T would permit, but I have no idea how or why this gets mass out of the BH and makes it "evaporate."

    I am very interested in understanding more about BHs, mainly because a pair of them are the villains in my book Dark Visitor In it I consider several non standard possible sources of BHs. Magnetic monopoles being my favorite. They are very heavy, should have been produced in great quantity, but not many seem to be around now - Only evidence of them is the once observed current step in a superconducting ring that did correspond with a single monopole passing thru the ring.

    One of my "off beat" theories (I have several - see thread "What Price Free Will" and "Time Does NOT Exist - Math Proof") is that the early universe was not at all like it is thought to be. There was recently some news to this effect also - something to do with there being too many already well formed galaxys, if memory serves.

    I think that the magnetic monopoles did form as theory predicts they should have and and unlike the neutral matter (not yet ionized by starlight) they have a long range means of mutual attraction and formed many micro black holes, which served as the seeds for stars formation. I.e. micro BHs are a local gravitational center that is able to collect molecules still too warm to mutually condense into a micro drop of hydrogen as a seed for others to adhere to.

    I am not so well informed as others here - so I ask leading questions, trying not to look too foolish by coming right out with some of my "crazy ideas." (that would get them immediately dismissed and me the "crackpot" label I may well deserve, for some of them.) I want to get others to think about things related to BHs. I have succeeded with Space Tiger - he is writing a paper as direct result of some of my questions. Perhaps I will, with my questions provoke the same in Hellfire (or you?) In any case, I am sorry if I annoyed you, but I don't think I am doing anything wrong - perhaps some good, if I induced some guy half my age to publish or even only rethink what he/she "knows." - That is the best thing an old cogger like me can do. - I am too lazy to publish myself any more and not interested in fame, career advancements, or even money with my book, which you can read for free. etc.

    PS to SpaceTiger, if you are reading: The more I think about it, the stronger my view that the rate of "vacuum polarization" inside the Earth is OOM lower than in vacuum - The Casimer effect should be strong when the "space between the plates" is essentially zero. I would even accept that there is no vacuum polarization inside "solid" matter. If there is, would it not interfere with the pairing of electrons that permits superconductivity to exist?
    Last edited: Mar 20, 2005
  15. Mar 20, 2005 #14


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    That's probably not going to happen, as my studies seem to be indicating that the question I had been pondering is moot. I'm going to keep it in the back of my mind, though. I'll post my work when I'm sure it is or isn't publishable.

    I'm not an expert on vacuum polarization, but I'm not sure you understand the magnitude of difference required here. If the 1 kg black hole entered conditions even vaguely resembling a vacuum, the decay would occur in [tex]10^{-16}[/tex] seconds. Given that there is a lot of empty space inside of a solid lattice (neutral and otherwise), there's no reason to think that the BH would survive for very long. The question is still somewhat open for much larger mass BHs (that is, I'm willing to accept that the Hawking decay limit can be prolonged a little bit), but not for 1 kg.
  16. Mar 20, 2005 #15
    Yes - I have not tried to do the numbers but eating up 1Kg in 10^-16 sec in 0.5 Mev bites (each the rest mass of the surviving member of the vacuum polarization pair) is a tremendous production and capture rate of Vac. Polarization pairs on /near the tiny surface of the event horizon.

    I am in no position to argue with Hawkings and the few others who can follow him, but as I don't even have the faintest idea how the mass gets out of the black hole to reduce its mass by even 0.5Mev for one swallowed electron, I keep holding my endorsement of the "evaporation" of BHs back - just silly but I never was big on accepting proclamations by small groups when what they are saying just does not seem to fit in with other things I "know." At least I want to hold out for the possibility that inside admittedly very empty "solids" there may be zero production of vacuum polarization pairs. I am also troubled by fact that when the BH swallows an electron, how does it know wheather or not it was a member of a pair. If yes, then lose 0.5Mev of mass, If no, don't lose any mass, instead gain 0.5Mev? That seems silly to me - how is the BH hole so smart?

    If there were such horrendous production inside a super conductor, why would some of the recently born positrons not annihilate with one member of the "exchange energy" electrons that can not scatter off phonons? Seem to me that a lot of newly minted positrons inside a super conductor would also in much less that 10^-16 sec have it a normal conductor - after all the total mass of the superconduction electrons is probably less that your one kg of the BH. Further more, the force attracting the positron to the the nearest electron of the super conducting pair is electrical, much stronger than gravity.

    I guess I am just too stubborn or worried too much about other implications to swallow things on the bases of authority. Perhaps until you know more about why this is nonsense, we should just agree to disagree on the rate of vacuum polarization inside solids (your "a few OOM different at most" vs my "may not even occur")
    Last edited: Mar 21, 2005
  17. Mar 20, 2005 #16


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    Or perhaps you should do the research yourself. Why are you relying on me for this? You seem to have a pretty good grasp of the subject. My intuition (and current theory) tells me that it's not going to work, so it's not really worth it for me to spend the time doing more research. If yours tells you otherwise, then the ball's in your court.
    Last edited: Mar 20, 2005
  18. Mar 20, 2005 #17


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    I just wished to comment on tiny black holes in general. The cosmic background gamma ray flux places severe constraints on their numbers [they cannot exist in large numbers].
  19. Mar 20, 2005 #18
    resent findings of metal rich quazars and stars
    point to a flaw in the total H with a small He post big bang univerce
    it was far lumpier far earlyer then "they thought"
    maybe every sized lumps very shortly post bigbang will be proved
    sure looks to be heading that way from the newest data
  20. Mar 21, 2005 #19
    Can you amplify? I prefer brief explanations as to how gamma rays imply this, but ref is OK.

    Small Black Holes, even if more numerious that the currently active stars (as I think they may be.), would rarely even slightly (much less that 1 degree) deflect a gamma ray. Their capture cross section must be an extremely small fraction of the night sky.

    I especially doubt gamma rays rule out many small BHs since we are not even sure what makes them. I don't beleve it, but I could agrue that the highest energy gamma rays are the result of "gravity assists" scatterings off of these numerious small black holes. - Seem to be as good as any other explanation I have read.

    Again, please justify your claim.
    Last edited: Mar 21, 2005
  21. Mar 21, 2005 #20
    Thanks for the details - I think this was what I read recently and referred to.
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