Dark Matter Decoupling from Plasma

[Trixie Mattel]

Hello,

I have been reading about how Dark Matter particles might possibly be made up of the lightest sterile right handed neutrino.

I was wondering, why exactly does the dark matter particle have to decouple from the plasma when it is formed?

 

[mfb]

All dark matter candidates had to stop interacting (significantly) with regular matter at some point, otherwise they would not be dark.