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How much mass per unit volume do known dark matter have, for instance in the Bullet Cluster? Does the density vary in space, for example, do individual dark matter structures have denser cores?

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  • $\begingroup$ But surely the fact that you mention the bullet cluster means you have seen the pictures showing the dark matter density variation compared with that of the baryons (hot gas). What is it exactly that you want to know? $\endgroup$ – ProfRob Nov 19 '16 at 11:56
  • $\begingroup$ @RobJeffries I have no grip on if dark matter is as dense as baryons and spread out over larger volumes, or if it has much higher densities than baryons where it has been detected. Bullet cluster mass contour plots show denser cores, but is that generally the case? A galactic "dark matter halo" sounds like a more evenly distributed sphere. $\endgroup$ – LocalFluff Nov 19 '16 at 14:13
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    $\begingroup$ See Einasto profile or Navarro-Frenk-White profile for models of dark matter density in a galaxy. Of course it is not uniformly distributed, it is affected by gravity. $\endgroup$ – ProfRob Nov 19 '16 at 14:30
  • $\begingroup$ @RobJeffries So if I get it correctly, dark matter density tends to decrease a bit faster than with the cube as a function of the radius in the NFW model. It still beats me if this is different from how concentrated baryonic matter is in galaxies and clusters. $\endgroup$ – LocalFluff Nov 19 '16 at 15:36

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