How do we detect and study dark matter in our universe?

[wolram]

http://arxiv.org/abs/astro-ph/0607621

An interesting look at the equiptment in use to detect DM.

 

[Mike2]

Isn't Dark Matter supposed to exist around ANY gravitating body, clusters, galaxies, stars, and planets? Have we ever seen a galaxy that does not seem to have a dark matter halo? If so, then it would seem that Dark Matter would have to be some sort of gravitational effect (on perhaps the zero point energy), right?

 

[SpaceTiger]

Isn't Dark Matter supposed to exist around ANY gravitating body, clusters, galaxies, stars, and planets?

That will depend upon the mass of the dark matter particle. A neutrino-mass particle, for example, would have difficulty remaining bound to a star or planet. I believe that even the heaviest of proposed dark matter particles would contribute negligibly to the mass of bodies in the solar system. However, the density of such particles near the center of the sun might be large enough that they would produce an annihilation signature detectable by neutrino observatories.

Have we ever seen a galaxy that does not seem to have a dark matter halo?

There have been elliptical galaxies observed that do not appear to have dark matter:

http://www.arxiv.org/abs/astro-ph/0308518"

If so, then it would seem that Dark Matter would have to be some sort of gravitational effect (on perhaps the zero point energy), right?

I don't see how this follows. In CDM models, I find it rather difficult to explain how a massive galaxy could be formed without dark matter.

 

[Chronos]

Ditto, ST. It is very difficult to explain how massive galaxies formed so quickly in the early universe without dark matter. That, to me, is the most compelling evidence of a DM dominated universe, unless of course BBT is wrong - which would open up a kettle of fish more than a few days old.

 

[SpaceTiger]

Ditto, ST. It is very difficult to explain how massive galaxies formed so quickly in the early universe without dark matter. That, to me, is the most compelling evidence of a DM dominated universe, unless of course BBT is wrong - which would open up a kettle of fish more than a few days old.

That isn't quite what I meant, but is a good point. Galaxy formation is difficult in the absence of dark matter.

All I meant is that the dark matter in the early universe was well mixed with the baryonic matter. Any overdensity that collapsed into a galaxy would have contained significant quantities of both. There are methods of removing the baryonic matter (such as stellar outflows), but I don't know how a massive galaxy could shed its dark matter.