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Dark Matter (Illustrations)
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What the Universe is Made of
Most of the Universe is dark. The protons, neutrons and electrons that make up the stars, planets and us represent only a small fraction of the mass and energy of the Universe. The rest is dark and mysterious. X-rays can help reveal the secrets of this darkness. X-ray astrophysics is crucial to our understanding not only of the Universe we see, but the quest to determine the physics of everything.
(Credit: NASA/CXC/M.Weiss)
Chronicle Article: The Universe |
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X-ray Distance Measurement Technique
This set of illustrations shows the technique used to make distance
measurements to galaxy clusters. Chandra's observations are used to
determine the ratio of the mass of the hot gas and the mass of the dark
matter in different galaxy clusters. This "gas fraction" depends on the
assumed distances to the clusters, which in turn depends on the amount of
matter and dark energy in the Universe. Because galaxy clusters are
extremely large, the gas fraction should be the same for every cluster, and
so the distances to the clusters are adjusted to satisfy this
requirement. Each of these 3 illustration shows Chandra in the top left,
observing a galaxy cluster, shown in the top right (in red). The relative
amounts of hot gas (in red) and dark matter (in blue) are shown at the
bottom, with the green marker giving the expected, correct amount. The
first illustration shows a gas fraction that is too small, implying that
the distance to the cluster is too small, the second shows the correct gas
fraction and distance, and the third illustration shows a gas fraction and
distance that are too large.
(Credit: NASA/CXC/M.Weiss)
View X-ray Distance Measurement Technique animation
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Energy Distribution of the Universe
The new Chandra observations include estimates of the total energy content
of the Universe. As shown in this illustration, dark energy is estimated to
contribute about 75% of the energy in the Universe, dark matter about 21%
and normal matter about 4%. Only the normal matter can be directly detected
with telescopes, and about 85% of this is hot, intergalactic gas, as
detected in Chandra observations of galaxy clusters.
(Credit: NASA/CXC/M.Weiss)
Related Field Guide
Chronicle Article: The Wonderful (And Fearful) Dark Side
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Three Possible Futures for the Universe
This illustration shows three possible futures for the Universe, depending
on the behavior of dark energy, by showing how the scale of the Universe
may change with time. If dark energy is constant, as the new Chandra
results suggest, the expansion should continue accelerating forever. If
dark energy increases, the acceleration may happen so quickly that
galaxies, stars, and eventually atoms will be torn apart, in the so-called
Big Rip. Dark energy may also lead to a recollapse of the Universe, in the
Big Crunch. The illustration also shows the early decelerating expansion of
the Universe, followed by the accelerating phase that started about 6
billion years ago.
(Credit: NASA/CXC/M.Weiss)
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Animation Stills: Effects of Dark Energy
These still images show the expansion history of the Universe by modeling
the Universe as a two-dimensional grid of galaxies. The Big Bang, shown
as a flash of light, is immediately followed by rapid expansion of the
Universe. This expansion then slows down because of the gravitational
attraction of the matter in the Universe. As the Universe expands, the
repulsive effects of dark energy become important, causing the expansion
to accelerate.
(Credit: NASA/STScI/G. Bacon)
View Animation of the Effects of Dark Energy
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Dark Matter
X-ray telescopes have discovered vast clouds of multimillion degree gas in clusters of galaxies. An X-ray image has been superimposed on an optical picture of a cluster of galaxies. This image was taken by ROSAT and shows hot gas highlighted in false red color.
(Illustration: Richard Mushotzky(GSFC/NASA),ROSAT,ESA,NASA)
Related Field Guide |
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Still Image from Dark Matter Animation
Clues from Chandra have enabled scientists to constrain the
size of dark matter particles in galaxy clusters. Dark matter is the
invisible and unknown material that constitutes about 80% of the matter
in the Universe.
(Credit: NASA/SAO/CXC)
Related Field Guide
Animations & Video: Dark Matter |
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