What is the temperature of cold & hot dark matter?

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SUMMARY

The discussion clarifies that cold and hot dark matter do not possess well-defined temperatures. Hot dark matter is characterized as highly-relativistic and was historically thought to interact more strongly, while cold dark matter is non-relativistic and interacts weakly. The concept of temperature applies only to collisionally dominated ensembles of particles that follow specific statistical distributions, making it nonsensical to assign a temperature to individual particles.

PREREQUISITES
  • Understanding of dark matter classifications: hot and cold dark matter
  • Familiarity with relativistic and non-relativistic physics
  • Knowledge of statistical mechanics and particle ensembles
  • Basic concepts of particle interactions and their implications
NEXT STEPS
  • Research the properties of hot dark matter and its implications in cosmology
  • Explore the role of cold dark matter in structure formation in the universe
  • Study statistical mechanics to understand temperature in particle systems
  • Investigate the interactions of dark matter with baryonic matter
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Astronomers, physicists, and cosmologists interested in the properties and behaviors of dark matter in the universe.

nargesh
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what is the temperature of cold & hot dark matter?
 
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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.
 

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