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.
NASA scientists have discovered proof of dark matter:
Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. The discovery, using NASA's Chandra X-ray Observatory and other telescopes, gives direct evidence for the existence of dark matter.
"This is the most energetic cosmic event, besides the Big Bang, which we know about," said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
This is significant because dark matter has been a concept that held the universe together but, since it was invisible, many scientists have doubted its existence at all. Dark matter has been used as an explanation for why Einstein's theory of relativity breaks down when blown up to cosmic distances, beyond just our solar system. That is, in certain places within the universe, gravity becomes stronger where Einstein's theory says it should be weaker. "Dark matter" is one explanation for why this happens. Cosmic Variance has a great explanation of what it's all about, and how this picture illustrates dark matter's existence.
In the Bullet Cluster, more formally known as 1E 0657-56, we actually find two clusters of galaxies that have (relatively) recently passed right through each other. It turns out that the large majority (about 90%) of ordinary matter in a cluster is not in the galaxies themselves, but in hot X-ray emitting intergalactic gas. As the two clusters passed through each other, the hot gas in each smacked into the gas in the other, while the individual galaxies and the dark matter (presumed to be collisionless) passed right through.
This is just a brief excerpt, but the rest of CR's post is worth reading, so you can sound smart when you tell other people about this.
[via Pharyngula]
Comments