Proposed forms of it include massive astronomical compact halo objects and (*) weakly interacting massive particles, or MACHOs and WIMPs.
One postulated type of this entity is known as the "self-interacting" type. The galaxy rotation problem is indirect evidence for its existence. It is grouped into the categories of hot, warm, and cold, based on the speed at which it travels. Proposed forms of it include massive astronomical compact halo objects and (*) weakly interacting massive particles, or MACHOs and WIMPs. For 10 points, name this hypothesized type of matter which accounts for 80% of the matter in the universe.
One postulated type of this entity is known as the "self-interacting" type.
{dark} matter [prompt on {dark energy} until "{matter}"]