Warm dark matter

Warm dark matter (WDM) is a hypothesized form of dark matter that has properties intermediate between those of hot dark matter and cold dark matter, causing structure formation to occur bottom-up from above their free-streaming scale, and top-down below their free streaming scale. The most common WDM candidates are sterile neutrinos and gravitinos. The WIMPs (weakly interacting massive particles), when produced non-thermally could be candidates for warm dark matter. In general, however the thermally produced WIMPs are cold dark matter candidates.

keVins and GeVins

One possible WDM candidate particle with a mass of a few keV comes from introducing two new, zero charge, zero lepton number fermions to the Standard Model of Particle Physics: "keV-mass inert particles" (keVins) and "GeV-mass inert particles" (GeVins). keVins are thermally overproduced, though the entropy production from the decays of unstable GeVins suppresses their abundance to the correct value. These particles are considered "inert" because they only have suppressed interactions with the Z boson. Sterile neutrinos with masses of a few keV are possible candidates for keVins. The sterility of such neutrinos would allow them to have masses of about 1 keV.

References

• Constraining warm dark matter candidates including sterile neutrinos and light gravitinos with WMAP and the Lyman-α forest
• King, S. & Merle, A. (2012) Warm Dark Matter from keVins. IOP Science, Journal of Cosmology and Astroparticle Physics, 1208 (2012) 016. doi: 10.1088/1475-7516/2012/08/016.
• The first star formation in WDM Universe
• W.B. Lin, D.H. Huang, X. Zhang, R. Brandenberger, Non-Thermal Production of WIMPs and the Sub-Galactic Structure of the Universe Phys. Rev. Lett. 86, 954, 2001.
• Millis, John. Warm Dark Matter. About.com. Retrieved 23 Jan., 2013. http://space.about.com/od/astronomydictionary/g/Warm-Dark-Matter.htm.

See also

• Dark matter
  • Hot dark matter (HDM)
  • Cold dark matter (CDM)
• Lambda-CDM model
• Modified Newtonian Dynamics

Further reading

• Bertone, Gianfranco (2010). Particle Dark Matter: Observations, Models and Searches. Cambridge University Press. p. 762. ISBN 978-0-521-76368-4. 

v t e Dark matter Forms of dark matter Baryonic dark matter Cold dark matter Hot dark matter Light dark matter Mixed dark matter Warm dark matter Self-interacting dark matter Hypothetical particles Axino Axion Chameleon particle Holeum LSP Minicharged particle Neutralino Sterile neutrino SIMP WIMP Theories and objects Cuspy halo problem Dark fluid Dark galaxy Dark matter halo Dark radiation Dark star Dwarf galaxy problem ELKO field Halo mass function Massive compact halo object Mirror matter Navarro–Frenk–White profile Scalar field dark matter Search experiments ADMX AMS-02 ANAIS ArDM ATIC CAST CDMS COUPP CRESST DAMA/LIBRA DAMA/NaI DarkSide DEAP DMTPC DRIFT EDELWEISS EURECA KIMS LUX MOA Multidark OGLE PAMELA PICASSO PVLAS SIMPLE SNOLAB UKDMC WARP XENON ZEPLIN-III Potential dark galaxies HE0450-2958 HVC 127-41-330 Smith's Cloud VIRGOHI21