Why do dark matter and baryon matter have different distributions?

[Demystifier]

Dark matter is distributed in halos around visible galaxies, while baryon matter is distributed in spiral-shaped visible galaxies. Where does this difference come from?

 

[Orodruin]

Baryon matter has the ability to radiate away energy through its electromagnetic interactions, which leads to the ability to clump together in more tightly bound systems.

Edit: Also, not all galaxies are spiral galaxies, but they are generally more tightly bound than their halos.

 

[anorlunda]

Your question gives me the chance to cite one a fun paper. Dark matter doesn't radiate of course. If it did it wouldn't be dark. The consequences of that are given in the paper.

The picture above is from a very entertaining paper, The Potato Radius: a Lower Minimum Size for Dwarf Planets you might have fun reading it.

 

[Orodruin]

Dark matter doesn't radiate of course.

Caveat: At least not very strongly.

 

[anorlunda]

Caveat: At least not very strongly.

The question and answer remind me of the fuzzy wuzzy poem. If I was more literate, I could make an analogous poem about dark matter.

Fuzzy Wuzzy was a bear.
Fuzzy Wuzzy had no hair.
Fuzzy Wuzzy wasn't fuzzy was he?