What characteristic is required for the favored Weakly Interacting Massive Particles (WIMPs) candidates?

They must be slow-moving (cold), non-collisional, and chemically distinct from known particles.

The Dark Matter Hypothesis requires the invisible substance composing the massive halos surrounding galaxies to possess very specific physical characteristics to explain the observed dynamics without disrupting known physics in other domains. The favored conceptual framework involves what is often termed 'cold' dark matter. This implies that the particles must be slow-moving relative to the speed of light, allowing them to clump gravitationally into the required halo structure. Furthermore, they must be non-collisional, meaning they pass through each other and through baryonic matter without strong interactions other than gravity. Finally, they must be chemically distinct, meaning they are not made of protons, neutrons, or electrons—the components that form normal stars, planets, and gas clouds.