In my understanding, galaxy clusters contain dark matter halos, which in turn contain subhalos, and the subhalos are what surrounds individual galaxies. I know that is a simplified picture, but I am just trying to figure out if it is correct in general. Additionally, when people talk about "substructure," does that apply to halos or to subhalos (or sometimes both)? My question stems from reading different papers where these terms seem to be used in slightly different ways. For example, here they talk about substructures as being individual subhalos, but I have heard the term in reference to all structure smaller than the cluster itself.

  • $\begingroup$ You basically have it. Halos have subhalos and subhalos have subhalos and on and on. Subhalos are also halos, especially if they hold a galaxy or a cluster. Substructure is any contained structure, but if the discussion is mainly about dark matter, then the substructure is the subhalos. $\endgroup$
    – eshaya
    Feb 9, 2021 at 22:14
  • $\begingroup$ What does "DM" mean? $\endgroup$
    – uhoh
    Feb 9, 2021 at 22:52
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    $\begingroup$ @uhoh I'm assuming it's dark matter. The OP's title is too long to expand "DM". $\endgroup$
    – WarpPrime
    Feb 10, 2021 at 2:09
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    $\begingroup$ Interesting question! I've adjusted the wording of your title to remove the abbreviation and to remove some words that probably aren't needed for the title. How does this look? (added some more tags as well) $\endgroup$
    – uhoh
    Feb 10, 2021 at 6:15


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