Comment by hermitcrab
9 hours ago
Halo implies empty (or low density) at the center. The 'normal' matter is denser at the center of a galaxy. I'm trying to understand why the difference.
>since dark matter interacts less
With electromagnetism or gravity?
Did a bit more reading. I was thinking of a halo like an angel's halo, a disk with greater density near the edge and less at the center. But it seems that dark matter halos are roughly spherical with greatest sensity near the centre. In which case halo seems like a pretty poor name.
I wonder when exactly saints halos changed into rings in religious images. The older ones are all, well halo-shapped, but currently the only image people think of are the rings.
Probably from The Simpsons
1 reply →