Dark and Normal Matter split
Credit:Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.

Darkness into Light

Now this is where the hidden is made visible. Astronomers believe (when not arguing about Pluto) that the Universe is largely made of mysterious stuff called dark matter. There's plenty of evidence of its existence from the gravitational effect it has on bright visible matter, but aside from that its properties are unknown. Now astronomers have observed an experiment run by the Universe which sheds some light on the darkness. The image above is a optical image, an X-ray image and a gravity map of a collision between clusters of galaxies. This collision is the most powerful event since the Big Bang. In the above image, the X-ray map (in pink) shows the location of most of the "normal" matter. The gravity map, which shows the distribution of most of the gravitating matter, is in blue. The gravitating matter, dominated by dark matter, lies clearly beyond the normal matter. Astronomers believe that this is because dark matter interacts only via gravity, so that during the collision the dark matter was not slowed down as much as the normal, "visible" matter seen in X-rays.

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Each week the HEASARC brings you new, exciting and beautiful images from X-ray and Gamma ray astronomy. Check back each week and be sure to check out the HEAPOW archive!

Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:23:10 EDT