Cosmological behavior in galaxy baffles scientists

A new study has pointed to previously unseen behavior by concentrations of dark and visible matter in the formation of a merging galaxy cluster 2.4 billion light-years away. Scientists were baffled by the merging galaxy cluster known as Abell 520, where concentrations of visible matter and dark matter -- the invisible substance that makes up much of our universe -- have apparently come unglued. The findings of the observations, which were made using the NASA's Hubble Space Telescope, were published in a report in the Astrophysical Journal. "We were not expecting this," the study team's senior theorist, Arif Babul of the University of Victoria, said in a news release. "According to our current theory, galaxies and dark matter are expected to stay together, even through a collision. But that's not what's happening in Abell 520. Here, the dark matter appears to have pooled to form the dark core, but most of the associated galaxies seem to have moved on," he added. Observations like those of Abell 520 are humbling in the sense that in spite of all the leaps and bounds in our understanding, every now and then, we are stopped cold," Babul explained. Astronomer James Jee, a project scientist in the Department of Physics at UC Davis, said, "This result is a puzzle… Dark matter is not behaving as predicted, and it's not obviously clear what is going on. Theories of galaxy formation and dark matter must explain what we are seeing." The dark matter was first detected in 2007 during a survey aimed at measuring the masses of 50 galaxy clusters thanks to data from the Canada-France-Hawaii Telescope at Mauna Kea in Hawaii.