Warm–hot intergalactic medium

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The warm–hot intergalactic medium (WHIM) refers to a sparse, warm-to-hot (105 to 107 K) plasma that cosmologists believe to exist in the spaces between galaxies and to contain 40–50%[1] of the baryons (that is, 'normal matter' which exists as plasma or as atoms and molecules, in contrast to dark matter) in the universe at the current epoch.[2] Because of the high temperature of the medium, the expectation is that it is most easily observed from the ultraviolet and low energy X-ray emission. It can also be described as web of hot, diffuse gas. To locate the WHIM, researchers examined X-ray observations of a rapidly growing super massive black hole known as an active galactic nucleus, or AGN.[3]


Within the WHIM, gas shocks are created as a result of active galactic nuclei, along with the gravitationally-driven processes of merging and accretion. Part of the gravitational energy supplied by these effects is converted into thermal emissions of the matter by collisionless shock heating.[1]

In May 2010 a giant reservoir of WHIM was detected by the Chandra X-ray Observatory lying along the wall shaped structure of galaxies (Sculptor Wall) some 400 million light-years from Earth.[4][5]

See also[edit]


  1. ^ a b Bykov, A. M.; Paerels, F. B. S.; Petrosian, V. (February 2008), "Equilibration Processes in the Warm-Hot Intergalactic Medium", Space Science Reviews, 134 (1–4): 141–153, arXiv:0801.1008Freely accessible, Bibcode:2008SSRv..134..141B, doi:10.1007/s11214-008-9309-4 
  2. ^ Reimers, D. (2002), "Baryons in the diffuse intergalactic medium", Space Science Reviews, 100 (1/4): 89, Bibcode:2002SSRv..100...89R, doi:10.1023/A:1015861926654 
  3. ^ "Huge Chunk of Universe's Missing Matter Found". Space.com. Retrieved 2016-12-05. 
  4. ^ http://www.space.com/scienceastronomy/chandra-missing-matter-100511.html
  5. ^ http://www.skyandtelescope.com/astronomy-news/last-missing-normal-matter-is-found/