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HEA > ASCA > Scientific Results > Evolution of X-ray celestial bodies and deep

(8) Evolution of X-ray celestial bodies and deep space

Work is proceeding on determining the actual distance of distant galaxy clusters. This process makes use of the effect where cosmic microwave radiation is scattered by the high-temperature plasma that surrounds galaxy clusters. It combines X-ray observations with radio observations.

This is one method to determine the Hubble constant (basic quantity for the size of the universe) by using celestial bodies that have cosmological distances, and it has great significance.

Unique galaxy clusters that are X-ray bright, although barely visible at optical wavelengths when observed in the vicinity of gravitational lenses whose true form is unknown, have been discovered. This startling result shows that galaxy clusters already existed in the earliest period of the universe.

In the centers of many nearby galaxies, weak but steady X-ray sources are being discovered. These can be interpreted as sites where small quantities of gas are descending into giant black holes at the galactic centers, and the hypothesis that past active galaxy cores evolve into ordinary galaxies has become fact.

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Next: (9) X-ray observation of supernova explosion


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