- Hot dark matter
Hot dark matter is a
hypothetical form ofdark matter which consists of particles that travel withultrarelativistic velocities. The best candidate for the identity of hot dark matter is theneutrino . Neutrinos have very small masses, and do not partake in two of the four fundamental forces, theelectromagnetic interaction and thestrong interaction . They "do" interact by theweak interaction , andgravity , but due to the feeble strength of these forces, they are difficult to detect. A number of projects, such as theSuper-Kamiokande neutrino observatory, in Gifu, Japan are currently studying these neutrinos.Dark matter is matter that cannot be detected by
electromagnetic radiation , hence "dark". It is postulated to exist to explain how clusters andsupercluster s ofgalaxies formed after thebig bang . Data from galaxy rotation curves indicate that around 90% of the mass of a galaxy cannot be seen. It can only be detected by its gravitational effect.Hot dark matter cannot explain how individual galaxies formed from the big bang. The
microwave background radiation as measured by theCOBE satellite is very smooth and fast moving particles cannot clump together on this small scale from such a smooth initial clumping. To explain small scale structure in theUniverse it is necessary to invokecold dark matter . Hot dark matter therefore is nowadays always discussed as part of a mixed dark matter theory.ee also
*
Dark matter
**Warm dark matter (WDM)
**Cold dark matter (CDM)
*Lambda-CDM model
*Modified Newtonian Dynamics External links
* [http://astron.berkeley.edu/~mwhite/darkmatter/hdm.html Hot dark matter by Berkeley]
* [http://csep10.phys.utk.edu/astr162/lect/cosmology/darkmatter.html Dark Matter]
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