Temperature of cold and hot dark matter

[nargesh]

what is the temperature of cold & hot dark matter?

 

[zhermes]

Neither has a well-defined temperature.
The terms 'hot' and 'cold' refer to characteristics of the dark matter, and how they behave---namely, hot dark-matter would be highly-relativistic (and in the past, was believed to be more strongly interacting); while cold dark matter is non-relativistic (and incredibly weakly interacting).

'Temperature' is only well defined in a collisionally dominated ensemble of particles that are well described by certain statistical distributions. It doesn't really make sense to say what the temperature of a single particle (for instance) is.