Tuesday, May 15, 2007

"This is the strongest evidence yet for the existence of dark matter,"

WASHINGTON (Reuters) - A hazy ring of dark matter spawned by a colossal cosmic crash eons ago offers the best evidence to date that vast amounts of this mysterious stuff reside in the universe, scientists said on Tuesday.

Images taken by NASA's orbiting Hubble Space Telescope allowed astronomers to detect this ring of dark matter created by the collision of two galaxy clusters 5 billion light-years from Earth.

"This is the strongest evidence yet for the existence of dark matter," astronomer Myungkook James Jee of Johns Hopkins University in Baltimore told reporters.

Astronomers believe dark matter -- as opposed to ordinary matter making up the stars, planets and the like -- comprises about 85 percent of the universe's material, but evidence of it has been difficult to come by.

Dark matter cannot be directly seen. It does not shine or reflect light, but astronomers infer its existence in galaxy clusters by observing how its gravity bends the light given off by even more faraway galaxies. They do not know what it is made of, but think it could be a kind of particle.

Astronomer Richard Massey of the California Institute of Technology, not involved in the research, said the findings are facing skepticism within the astronomical community.


Dark Matter Ring Modeled around Galaxy Cluster CL0024+17
Credit: NASA, ESA, M. J. Jee & H. Ford et al. (Johns Hopkins U.)

Explanation: How do we know that dark matter isn't just normal matter exhibiting strange gravity? A new observation of gravitationally magnified faint galaxies far in the distance behind a massive cluster of galaxies is shedding new dark on the subject. The above detailed image from the Hubble Space Telescope indicates that a huge ring of dark matter likely exists surrounding the center of CL0024+17 that has no normal matter counterpart. What is visible in the above image, first and foremost, are many spectacular galaxies that are part of CL0024+17 itself, typically appearing tan in color. Next, a close inspection of the cluster center shows several unusual and repeated galaxy shapes, typically more blue. These are multiple images of a few distant galaxies, showing that the cluster is a strong gravitational lens. It is the relatively weak distortions of the many distant faint blue galaxies all over the image, however, that indicates the existence of the dark matter ring. The computationally modeled dark matter ring spans about five million light years and been digitally superimposed to the image in diffuse blue. A hypothesis for the formation of the huge dark matter ring holds that it is a transient feature formed when galaxy cluster CL0024+17 collided with another cluster of galaxies about one billion years ago, leaving a ring similar to when a rock is thrown in a pond.


Tommy said...

I know dark matter exists, I used to see it all the time in my childrens' diapers!

Stardust said...

tommy, you are so funny.

Yes, we parents DO know about mysterious dark matter now, don't we? LOL!

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