HEA > ASCA > Scientific Results > Dark matter

(7) Distribution and total mass of dark matter

ASCA is observing the distribution of the high-temperature plasma that surrounds galaxy clusters. Calculations of the gravitational mass required to bind the plasma are confirming that the gravitational mass of the dark matter is 5 to 10 times more than observable matter.

Combined with the mass of observable matter from the theory of element creation in the beginning of the universe, this suggests that the mean mass of the universe is only one part of several of the critical mass of the universe.

A hierarchical structure in the distribution of dark matter, which involves a galaxy-cluster-scale distribution and a smaller galaxy scale distribution, has been identified for the first time. This is an important clue toward understanding structure formation in the universe.

The results of measuring the distribution of dark matter in certain types of galaxy clusters are seen as being consistent with numerical calculations that are based on the "cold dark matter" hypothesis.

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ISAS/JAXA Department of High Energy Astrophysics