Mixed dark matter
Encyclopedia
A theory of dark matter
which was promising up to the late 1990s.
"Mixed" dark matter is also called Hot + Cold Dark Matter. Hot Dark matter has only one known form - neutrinos, although other forms are speculated to exist. Cosmologically important dark matter is now believed to be pure Cold Dark Matter
. However, in the early 1990s the power spectrum of fluctuations in the galaxy clustering did not agree entirely with the predictions for a standard cosmology built around pure Cold Dark Matter. Mixed Dark Matter with a composition of about 80% cold and 20% hot (neutrinos) was investigated and found to agree better with observations. This model was made obsolete by the discovery in 1998 of the acceleration of universal expansion, which eventually led to the Dark Energy + Dark Matter paradigm of this decade.
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
which was promising up to the late 1990s.
"Mixed" dark matter is also called Hot + Cold Dark Matter. Hot Dark matter has only one known form - neutrinos, although other forms are speculated to exist. Cosmologically important dark matter is now believed to be pure Cold Dark Matter
Cold dark matter
Cold dark matter is the improvement of the big bang theory that contains the additional assumption that most of the matter in the Universe consists of material that cannot be observed by its electromagnetic radiation and whose constituent particles move slowly...
. However, in the early 1990s the power spectrum of fluctuations in the galaxy clustering did not agree entirely with the predictions for a standard cosmology built around pure Cold Dark Matter. Mixed Dark Matter with a composition of about 80% cold and 20% hot (neutrinos) was investigated and found to agree better with observations. This model was made obsolete by the discovery in 1998 of the acceleration of universal expansion, which eventually led to the Dark Energy + Dark Matter paradigm of this decade.