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Thread: Dark matter mass scale?

  1. #1
    Join Date
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    Dark matter mass scale?

    So we all know I am dissecting the following simulator:
    https://www.compadre.org/OSP/documen...512&DocID=2444

    FYI it can be run with:
    Code:
    java -jar ejs_astro_GalaxyRotation.jar
    If you click on "Show dark matter panel", what does "Dark matter mass scale" mean? Is that the dark matter density uniform in the galaxy?


    Thanks a lot,
    philippeb8

  2. #2
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    No, the inferred distribution of dark matter is concentrated toward the center of the galaxy, just not as sharply as that of the stars. My wild guess is something analogous to the scale height of our atmosphere, that is, the height at which the density drops by a factor of e.

  3. #3
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    What are the units of "mass scale"?
    I believe it relates to the mass-energy of the hypothetical dark matter particle you're modelling - its distribution will vary according to that energy, which would be measured in electron-volts or something similar.

    Grant Hutchison

  4. #4
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    Quote Originally Posted by Hornblower View Post
    No, the inferred distribution of dark matter is concentrated toward the center of the galaxy, just not as sharply as that of the stars. My wild guess is something analogous to the scale height of our atmosphere, that is, the height at which the density drops by a factor of e.
    So this variable in the simulator is called and one of the curve is defined as this:



    Where:


    ...

    So it's just a constant inside a square root. I'm not sure if this equation sounds familiar to anybody but you're right it can't be uniform.

  5. #5
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    Quote Originally Posted by grant hutchison View Post
    What are the units of "mass scale"?
    Sorry I can't tell but guess from the equation above.

  6. #6
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    Quote Originally Posted by philippeb8 View Post
    Sorry I can't tell but guess from the equation above.
    Never mind all this, it's my homework now. I was just wondering if it was fitting a well-known pattern that I was not aware of.

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