Not cold

The not cold ( cold spot in English) is the name given to an area of the celestial Sphère in the direction of which the Température of the cosmological diffuse Fond presents a surprisingly large variation compared to the fluctuations observed in the other directions. This area was identified in 2004 in the data published by the Artificial satellite WMAP one year earlier. In 2007, it was shown that the relatively cold temperature of this area of the sky results from what a broad matter zone relatively not very dense is there. This zone, as the remainder of the universe, is prone to the Expansion of the universe, but the expansion is slightly faster there. So the diffuse Photon S of the cosmological bottom which cross it undergo a Décalage towards the red more important than the average, for with final giving the impression which the universe is colder in this area. This effect, known under the name of Sachs-Wolfe Effect integrated, was highlighted in 2007 by a Grand statement carried out by the Broad Very Array . It is about the first direct description of integrated the Sachs-Wolfe effect, this one indirectly having however already been highlighted in the data of WMAP.

Detection

The cosmological diffuse Fond is the oldest radiation of the universe. It was emitted a few hundreds of thousands of years only after the Big Bang. At that time, the universe was extremely homogeneous, also its temperature was it almost identical in any point. The observation today of this radiation confirms this fact: the temperature of the cosmological diffuse bottom is almost the same one in all the directions. However, the current universe is not also homogeneous: the matter is mainly gathered within the Galaxie S, forming they-even of the larger structures (Galaxy cluster) between which one finds matter zones relatively empty. The old universe, as seen via the cosmological diffuse bottom, carried already the germs of these great structures to come: there existed already zones slightly denser (and more heats) and others slightly less less dense (and colder), which results in weak variations in the temperature of the cosmological diffuse bottom according to the direction of observation. The standard Modèle of cosmology makes it possible today to predict in a statistical way the distribution in the face and amplitude of these surdensities and these sousdensities. It is thus possible to predict which is the probability of observing a zone colder than the average of a given size. The cold point was thus detected within the framework of an analysis aiming at determining if the structure specifies cosmological diffuse bottom were compatible with the standard model of cosmology: it seems an abnormally cold and extended area of the vault of heaven.

Localization

The center of the area is located in the Constellation of Éridan. It has the following coordinates:

See too

External bonds

  • a " trou" giant in the universe: direct proof of black energy?

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