Q and A of the Day: Anti-Dark Matter?

Since we've had a couple of stories on dark matter recently, we wanted to feature some Q and A's we've received on the topic over the years.

Q: Is it possible for the existence of an 'anti-dark matter?' It was long predicted for the existence of anti-matter in theory so it seems plausible to me.

The nature of dark matter is unknown. A substantial body of evidence indicates that it cannot be baryonic matter, i.e., protons and neutrons. The favored model is that dark matter is mostly composed of exotic particles formed when the universe was a fraction of a second old. Such particles, which would require an extension of the so-called Standard Model of elementary particle physics, could be WIMPs (weakly interacting massive particles), or axions, or sterile neutrinos.
Cosmic Timeline Illustration Credit: NASA/CXC/M.Weiss

A: It depends on what dark matter is. If it is slow moving dark particles as many theorists predict, then one could assume there would be anti-particles. However, we would then have to explain why there are so many more dark matter particles than anti-dark matter particles (the same problem we are faced with for matter and anti-matter) or explain where the anti particles are hidden.

For more information on the dark matter mystery, please visit the X-ray Field Guide on dark matter:
http://chandra.harvard.edu/xray_astro/dark_matter.html