Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why does the amount of dark matter increase the further away from the

  1. Sep 6, 2014 #1
    Why isn't the dark matter just randomly distributed? How does it know where to go? Why does the amount of dark matter increase the further away from the galaxy's center?
     
  2. jcsd
  3. Sep 6, 2014 #2

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    Dark matter yo-yo's in and out of the local center of gravity. It gains velocity as it approaches the center of gravity and slows as it exits. Because of its low velocity in the 'halo' region, it tends to spend more time there.
     
  4. Sep 6, 2014 #3
    You might ask the same questions about visible matter in Galaxies. It is not evenly distributed either, especially not in spiral galaxies.

    The distribution of mass is likely a result how how different galaxies formed.

    We do not believe dark matter would be changed by most normal astrophysical reactions other than gravity (friction, for instance), so where it tends to settle would be different than where normal baryonic matter would settle.
     
  5. Sep 6, 2014 #4

    phinds

    User Avatar
    Gold Member
    2016 Award

    Yes, but the point is more that it probably DOESN'T "settle". As Chronos pointed out, it yo-yos from one side of the galaxy to the other
     
  6. Sep 6, 2014 #5
    I have the same issue with long-period comets. It's almost as if they're avoiding us.
     
  7. Sep 6, 2014 #6

    phinds

    User Avatar
    Gold Member
    2016 Award

    You think it was something we said? :smile:
     
  8. Sep 6, 2014 #7
    I do not think anything really "settles", but without a way to measure the peculiar velocity of dark matter (as far as I know), I think the best we have are computer models.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Why does the amount of dark matter increase the further away from the
  1. Why just Dark Matter ? (Replies: 3)

Loading...