View Full Version : Dark Matter Halos? How About Disks, Too

2008-Sep-16, 01:50 PM
Scientists are trying to understand the invisible and hypothetical 'dark matter' – the stuff that we know exists by inference of its gravitational influence on the matter we can see. The most common held notion of dark matter is that it exists in 'halos' or clumps that surround galaxies. But a new study predicts [...]

More... (http://www.universetoday.com/2008/09/16/dark-matter-halos-how-about-disks-too/)

2008-Sep-17, 12:28 AM
How can the disk have half the density of the halo, wouldn't that make it a disk shaped DM void, rather than a structure?

2008-Sep-17, 12:45 AM
Since the dark matter halo does not rotate, from an Earth-based perspective it feels as if we have a ‘wind’ of dark matter flowing towards us at great speed.

I find dark matter difficult to grasp. If the dark matter isn't rotating, its not orbiting so why doesn't it just fall into the galactic nucleus? In the astro papers I've read that invoke dark matter it seems to have whatever properties it needs to explain what the author wants it to explain. It's self-annihilating or not, or interacts weakly or not at all, etc.