Darkmatter and supermassive blackholes

Discussion in 'Astronomy, Exobiology, & Cosmology' started by trgissel, Aug 8, 2005.

  1. trgissel Registered Member

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    Hi,

    I was just watching a program on supermassive blackholes and the program spoke about how the blackholes are not observable directly but only by the surrounding matter. This got me wondering what has disproven the possibility that darkmatter are really blackholes that have no longer has matter encircling it. The hypothesis would be that the blackholes are not observable because there is no matter close enough to make them observable but they would still add weight to the universe.

    Thanks for the patience in answering my question,

    Tom
     
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  3. superluminal I am MalcomR Valued Senior Member

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    Tom,

    I don't think there is anything that "disproves" at least some dark matter could be in the form of black holes. I think it's still a fairly open question.

    Brief Survey of Dark Matter Candidates
    -------------------------------------
    There is no shortage of ideas as to what the dark matter could be. In fact, the problem is the opposite. Serious candidates have been proposed with masses ranging from eV = kg (axions) up to (black holes). That's a range
    of masses of over 75 orders of magnitude! It should be clear that no one search technique could be used for all dark matter candidates.
    -------------------------------------

    Source:
    http://web.mit.edu/~redingtn/www/netadv/specr/345/node1.html
     
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  5. Anomalous Banned Banned

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    Your analysis are absolutely right.

    Have you heard about hypernova, there hypernovas are so powerful that the entire mass equivalent to our sun is converted into energy in a single explosion, that results in supposed the to be supremassive blackhole.

    These hypernovas are a result of Super massive Stars death. NOW, the point is that all such hypernovas are found to occur only at distances beyond 9 billion light years. Why ? because universe was much denser at that time.

    The universe near us dosent seem to be that dense today, because most of the matter became black hole 9 billion years ago. The missing matter is the dark matter and the dark matter is nothing but stars with no energy.

    Dark matter = Dead stars (not necessarily black holes)
     
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  7. Avatar smoking revolver Valued Senior Member

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  8. Dinosaur Rational Skeptic Valued Senior Member

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    The existence of Dark Matter seems necessary because there does not seem to be enough visible matter to provide mass appropriate to rate of expansion of the universe.

    I think that the motion of visible stars in various galaxies indicate that dark matter exists and that it is not concentrated in large black holes. Stars have been observed with speeds which would result in their escaping from their galaxy (or having much different motions from those observed) if the only gravity was due to the visible stars and a central black hole. Various computer simulations have suggested a diffuse distribution of the unseen matter.

    Astrophysicists (and physicists in general) have more of a sense of humor than people usually attribute to them. The simulations suggest two possibilities.
    • Weakly Interacting Massive Particles, to be known as WIMPs. These particles are quantum level entities which do not interact with matter or energy except for having mass contributing to gravitation effects. I think the simulations suggest a diffuse cloud of WIMPs spread over a galaxy size volume of space, and extending beyond the visible galaxy.

    • Some set of words resulting in the acronym Machos. I remember Massive something Halo Objects. I think this simulation suggests brown dwarfs or large asteroid-like objects which do not radiate. The simulations suggest that MACHOs form a 2D halo surrounding a galaxy.
    I think that MACHOs have been ruled out due to failure to observe some expected phenomena resulting from the existence of such objects. Perhaps they would result in gravitation lens effects on visible stars or other transit effects when a MACHO passed directly between an observer and a star.
     
  9. Boris2 Valued Senior Member

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    >>>>Some set of words resulting in the acronym Machos.

    MAssive Compact Halo Objects.
     
  10. Okeydoke Registered Senior Member

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    The real question is? Did Blackholes start out in the beginning as Supermassive Blacks Holes or did they evolve into them through a process called 'Galactic Cannibalism'? I believe the observational evidence supports the theory or maybe fact, that Black Holes in the beginning evolved into Supermassive Black Holes such as the probable case for the Supermassive Black Hole in the galaxy M-87.

    Okeydoke
     
  11. Anomalous Banned Banned

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    You are absloutely right,

    After the BigBang (or its equivalent) the primordial soup of hot gases (particles) were homogenous and rapidly expanding, but while they were expanding some areas collapsed due to gravity into massive stars due to the closeness of the universes particles, which immediately resulted in hypernovas of unpresidented scales resulting into supermassive Blackholes. Due to the closeness of the universes particles these blackholes further grew engulfing more surrounding matter this stage is called Quasar. After that these gaint blackholes became centers of all the galaxies we can see today. I mean they attracted the stars forming galaxies.
     
  12. Rom Registered Senior Member

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    But don't Black holes actually get smaller over time due to evaporation, either that or a galaxy will find its death at the centre of itself where the supermasive black holes are, but then its only those super Black holes that keep the galaxies from falling appart, after all galaxies are rotating and that would spread them out, another thing this whole Dark matter thing the damn figures never even out because as far as our maths has come the Earth might as well be flat, did anyone bother to think that good old empty space as a unit of measurement may account for some of that mass, time itself is a measuremnt which could account for some of that mass after all, suposedly before the big bang, time as we know it and space and dimensionality was compressed into nothingness, but here is something to think about, balanced and perfect would be the universe that containied nothing so why the hell should anything exist at all anyway?
     
  13. Okeydoke Registered Senior Member

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    Book a ticket to M-87 and find out.

    Okeydoke
     
  14. Dinosaur Rational Skeptic Valued Senior Member

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    A black hole without a source of matter available to be sucked in will evaporate.

    It is believed that a very small black hole will evaporate very fast. Very massive black holes will require some incredible amount of time to evaporate. I do not remember any of the relevant numbers. I wonder if this difference in time is analogous to the more rapid heat loss of smaller bodies due to the higher ratio between surface area and mass when compared to larger bodies.

    A search for "hawking radiation" might result in a site providing time estimates.

    The massive black holes at the center of galaxies will not start to evaporate until they have sucked in every bit of matter available to them. Thus the evaporation process might not start until a time orders of magnitude greater than the current age of the universe.
     
  15. blobrana Registered Senior Member

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    According to the theory, that’s not exactly correct; they emit Hawkins radiation as soon as an event horizon forms.
     
  16. Rom Registered Senior Member

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    What about the whole quantum foam theory that inside a black hole, matter can't exist the way it does out side the singularity and your have quantum foam, the stuff that makes the stuff that makes the fabric that makes the building blocks Blah Blah,
    Can anyone explain to be the whole time diferential between inside and outside the event horizon, as it is logical that this kind of distorion would cause friction of some kind though I believe to avoid paradox problems a singularity is not "naked" any one got any thoughts on this, and one more thing, if you could fly a ship to as close to the speed of light as possible at the black hole, could that extra gravitational tug push you over the light barrier, I assume this would displace energy backwards in time because the speed of light is limited to a rate of movement throught space in a given ammount of time
     
  17. Anomalous Banned Banned

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    if blackholes exist, then it shows us that gravity is most fundamental property of matter because G continues to exist even if matter is all crushed to be no longer called as matter we know.
     
  18. Odin'Izm Procrastinator Registered Senior Member

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    And what exactly is a dead star, and why does it not react with light in any way? Usually when stars die they form white dwarfs. If their a bit bigger, they form a neutron star, if they are even larger, they form a black hole.
     
  19. Odin'Izm Procrastinator Registered Senior Member

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    And black holes don't evaporate as nothing can escape from them, hence black hole, not even light is emited. Hawking radiation states that in a vacume particles are brought into creation at random, when one forms on the event horizon with its anti particle, the one beyond the event horizon is dispatched into space, while the other disapears into the black hole. So basically there is a constant addition of matter and anti matter at random instances into the universe.
     
  20. blobrana Registered Senior Member

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    Hum,
    The word on the street says that the particle that falls into the black hole carries with it <b>negative mass-energy</b>.
    We must remember that the two original particles formed were `virtual` (<i>and it is slightly different from matter/antimatter creation.</i>).

    The particle that is inside the black hole cancels some of the `matter` there; and the black hole losses mass.
     
  21. Anomalous Banned Banned

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    blackhole is figment of imagination premitive brains
     
  22. Odin'Izm Procrastinator Registered Senior Member

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    Aha but here is the paradox, When matter meets anti matter, it creates a quant of light, since that light cant escape out of the black hole, it stays there, so nothing escapes.
     
  23. Odin'Izm Procrastinator Registered Senior Member

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    It would have to be, since its a word created by humans, out of imagination.
     

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