APOD: 2002 August 20 - The Universe in Hot Gas
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2002 August 20
The Universe in Hot Gas
Credit & Copyright:
James Wadsley
(
McMaster U.
) et al.
Explanation:
Where is most of the normal matter in the Universe?
Recent observations
from the
Chandra X-ray Observatory
confirm that it is in
hot gas filaments strewn throughout the universe.
"Normal matter" refers to
known elements
and familiar
fundamental particles
.
Previously, the amount of
normal matter
predicted by the
physics of the early universe
exceeded the normal matter in
galaxies
and
clusters of galaxies
,
and so was observationally unaccounted for.
The
Chandra observations
found evidence for the massive and hot
intergalactic medium
filaments by noting a slight dimming in
distant quasar
X-rays
likely caused by hot
gas absorption
.
The
above image
derives from a
computer simulation
showing an expected typical distribution of hot gas in a
huge slice of the universe
2.7 billion
light-years
across and 0.3 billion light years thick.
The
distribution
of much more abundant
dark matter
likely mimics the normal matter,
although the
composition
of the
dark matter
remains mysterious.
Both the distribution and the
nature
of the even more abundant
dark energy
also remain unknown.
Tomorrow's picture:
The Perfect Spiral
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Authors & editors:
Robert Nemiroff
(
MTU
) &
Jerry Bonnell
(
USRA
)
NASA Technical Rep.:
Jay Norris
.
Specific rights apply
.
A service of:
LHEA
at
NASA
/
GSFC
&
Michigan Tech. U.