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(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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and total mass of dark matter
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of supernova explosion
ISAS/JAXA Department of High Energy Astrophysics
Last Modified: Wednesday, 21-Nov-2001 13:06:34 JST