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Thread: Cold or Warm dark matter

  1. #1 Cold or Warm dark matter 
    Forum Bachelors Degree PetTastic's Avatar
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    There was an interesting, but slightly confusing article on the BBC news website on dark matter.

    BBC News - Dwarf galaxies suggest dark matter theory may be wrong

    This chap's computer models suggest that cold dark matter does not fit observations of dwarf galaxies, and that warm dark matter may be a better fit.

    Most of my reading on warm dark matter seemed to indicate it had been dismissed for galaxy formation?

    Is it assumed or possible that warm dark matter cools by interaction with normal matter in large galaxies?
    I thought these were different particles altogether?


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  3. #2  
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    "Warm dark matter" is dark matter that moves at great speeds relative to it's source when created, like a neutrino. Such material would not easily form into structures in the early universe.

    I would say that there is definitely something funny going on in galaxy formation. There seems to be some hole in our information about the formation and rotation of galaxies that results in several systematic deviations from our expectations. I don't know what this it, though.


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  4. #3  
    Moderator Moderator Dishmaster's Avatar
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    It is believed that DM, if it exists, does not interact via electromagentism. Therefore, "cooling" warm DM seems to be very difficult at least.
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    Quote Originally Posted by Dishmaster View Post
    It is believed that DM, if it exists, does not interact via electromagentism. Therefore, "cooling" warm DM seems to be very difficult at least.
    Yes, good point
    Even if there was someway gravitational interaction could have a cooling effect. I now don't see how it would help anyway.
    You need the CDM at the start of the universe to form the first galaxies very early.

    What about his supernova disrupting the dwarf galaxy's formation, idea?
    Or possibly O-type stars that cleared out the gas, killing of other stars

    Other ideas are dark matter does not exist or interaction with other gallaxies.
    Is there anything in MOND papers about dwarf galaxies?
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    There is a lot about dwarf galaxies in the MOND lit. The MOND Literature in particular: The MOND Literature
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  7. #6  
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    Quote Originally Posted by PhysBang View Post
    There is a lot about dwarf galaxies in the MOND lit. The MOND Literature in particular: The MOND Literature
    I am workinjg on variants of the relativistic black hole hyperbolic galactic gravitational field hypotheis to explain the MOND effect and the details that do not fit MOND. I want to find someone with supercomputer access who would like to collaborate on simulatiions. Dwarf galaxies probably cannot even exist unless they have more than one very massive, if not supermassive, black hole embedded within. The complex field that this would produce wiill help explain peculiarities. The Bullet Cluster comes to mind.
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  8. #7  
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    Quote Originally Posted by PhysBang View Post
    There is a lot about dwarf galaxies in the MOND lit. The MOND Literature in particular: The MOND Literature
    Wow! Great Link! Thank you.
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  9. #8  
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    Would it be possible for neutrinos to be slowed down by a black hole via momentum exchange? (I'm going to go ahead and post a bigger version of that question in the New Hypothesis And Ideas section).
    Some clocks are only right twice a day, but they are still right when they are right.
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