NASA discovers new evidence of dark matter
{{date|August 21, 2006}}

New observations of the distribution of mass show clear evidence of the separation of [[w:dark matter|dark matter]] and normal matter, according to [[NASA]] scientists.

[[Image:Bullet_Cluster.jpg|thumb|right|250px|[[w:Bullet cluster|The Bullet Cluster]], 4 billion light years away from Earth, is formed by two [[w:Galaxy groups and clusters|galactic clusters]] colliding.]]

"This is the most energetic cosmic event, besides the Big Bang, which we know about," said Maxim Markevitch of the [[w:Harvard-Smithsonian Center for Astrophysics|Harvard-Smithsonian Center for Astrophysics]] and member of the NASA team that studied images collected with the [[w:Chandra X-ray observatory|Chandra X-ray observatory]], the [[w:Hubble Space Telescope|Hubble Space Telescope]], the European Southern Observatory's [[w:Very Large Telescope|Very Large Telescope]] and the [[w:Magellan (Telescopes)|Magellan optical telescopes]].

The observation supports the theory that the bulk of the universe is made up of invisible dark matter, which was detected by observing the gravitational force it exerted on visible matter.

"A universe that's dominated by dark stuff seems preposterous, so we wanted to test whether there were any basic flaws in our thinking," said team leader Doug Clowe of the [[University of Arizona]] at [[Tucson]]. "These results are direct proof that dark matter exists." 

Because the force of gravity can bend light, the team was able to detect the presence of dark matter through gravitational lensing.  Light emitted by objects that lie on the far side of the galaxy was distorted by a gravitational force in excess of the distortion expected by the visible matter present in the galactic collision. To make their discovery, the scientists trained their telescopes on a cluster of galaxies officially designated 1E0657-56, informally known as the bullet cluster because of its shape. 

The bullet shape is the result of the violent collision of a small galaxy cluster with another, larger cluster as normal matter in the galaxies interacts during the collision. Dark matter, however, does not experience any of the forces that affect normal matter, other than gravity, and ended up separating from the normal matter during the event.

These results will be published in an upcoming issue of [[w:Astrophysical Journal|Astrophysical Journal]] Letters.

== Sources ==

*{{source-pr|url=http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html
|title=NASA Finds Direct Proof of Dark Matter
|pub=NASA
|date=August 21, 2006}}

*{{source|url=http://www.space.com/scienceastronomy/060821_dark_matter.html
|title=Colossal Cosmic Collision Reveals Mysterious Dark Matter
|author=Robert Roy Britt
|pub=Space.com
|date=August 21, 2006}}

*{{source|url=http://news.bbc.co.uk/2/hi/science/nature/5272226.stm
|title=Team finds 'proof' of dark matter
|author=Paul Rincon
|pub=BBC News Online
|date=August 21, 2006}}

*{{source-pr|url=http://www.nasa.gov/home/hqnews/2006/aug/HQ_M06128_dark_matter.html
|title=NASA Announces Dark Matter Discovery
|pub=NASA
|date=August 14, 2006}}

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[[category:Physics]]
[[category:Space]]
[[category:Science and technology]]
[[Category:NASA]]
[[Category:North America]]
[[Category:United States]]
[[Category:Arizona]]
[[Category:Tucson, Arizona]]
[[Category:University of Arizona]]
[[Category:Hubble Space Telescope]]
[[Category:The Astrophysical Journal]]
[[Category:Dark matter]]
[[Category:European Southern Observatory]]
[[Category:Very Large Telescope]]

[[de:NASA entdeckt neuen Beweis für dunkle Materie]]
New observations of the distribution of mass show clear evidence of the separation of dark matter and normal matter, according to NASA scientists.

The Bullet Cluster, 4 billion light years away from Earth, is formed by two galactic clusters colliding.

"This is the most energetic cosmic event, besides the Big Bang, which we know about," said Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics and member of the NASA team that studied images collected with the Chandra X-ray observatory, the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope and the Magellan optical telescopes.

The observation supports the theory that the bulk of the universe is made up of invisible dark matter, which was detected by observing the gravitational force it exerted on visible matter.

"A universe that's dominated by dark stuff seems preposterous, so we wanted to test whether there were any basic flaws in our thinking," said team leader Doug Clowe of the University of Arizona at Tucson. "These results are direct proof that dark matter exists." 

Because the force of gravity can bend light, the team was able to detect the presence of dark matter through gravitational lensing.  Light emitted by objects that lie on the far side of the galaxy was distorted by a gravitational force in excess of the distortion expected by the visible matter present in the galactic collision. To make their discovery, the scientists trained their telescopes on a cluster of galaxies officially designated 1E0657-56, informally known as the bullet cluster because of its shape. 

The bullet shape is the result of the violent collision of a small galaxy cluster with another, larger cluster as normal matter in the galaxies interacts during the collision. Dark matter, however, does not experience any of the forces that affect normal matter, other than gravity, and ended up separating from the normal matter during the event.

These results will be published in an upcoming issue of Astrophysical Journal Letters.

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category:Physics
category:Space
category:Science and technology
NASA North America United States Arizona Tucson, Arizona University of Arizona Hubble Space Telescope The Astrophysical Journal Dark matter European Southern Observatory Very Large Telescope