A cluster of galaxies Dark matter core cannot be explained by current theories

Astronomers used the Hubble Telescope to discover what they believe is a clump of dark matter left over from wreckage between large clusters of galaxies. This finding could change the current theories about dark matter and how galaxies should be attached to this invisible at all times including when it is facing the shock of a collision. Abell 520 is a cluster of galaxies 2.4 billion light years away. The dark matter has formed itself into a core, and contains fewer galaxies than would be expected than if they were anchored together. When originally discovered in 2007 astronomers had claimed it was unreal, due to poor data, but further analysis from the hubble telescope confirms that the dark matter and galaxies are indeed, not attached. "Dark matter is not behaving as predicted, and it's not obviously clear what is going on. It is difficult to explain this Hubble observation with the current theories of galaxy formation and dark matter." The original theory was backed up by visible light and X-ray observations of another collision between to galaxy clusters called the Bullet cluster, which became an example of how galatic grouping should be. But after analyzing Abell 520 we believe the behavior of dark matter might not be as simple as we had thought. Its core contained a lot of dark matter and hot gas, but no luminous galaxies. "We know of maybe six examples of high-speed galaxy cluster collisions where the dark matter has been mapped. But the Bullet Cluster and Abell 520 are the two that show the clearest evidence of recent mergers, and they are inconsistent with each other. No single theory explains the different behavior of dark matter in those two collisions.” More data needs to be collected. Many theories have been proposed, but they are unsettling for astonomers.
This is issue is a very sensative thing. On one hand if we are wrong about how dark matter works to a high extent then it could start to affect other theories we have come up with and show us that we know very little about our universe. On the other hand this anomaly cannot easily be explained by informationwe currently have on the subject, which is very little because of dark matters properties it is very hard study. I personally think more data should be gathered before we really start to form opinions or hypotheses on the subject

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source:http://www.sciencedaily.com/releases/2012/03/120302101413.htm