1 AN UNEXPLAINED CLUMP OF DARK MATTER
Dark matter sounds ominous, but scientists believe that it comprises more than 80 per cent of all matter in the universe. It can’t be seen or directly detected because it doesn’t emit light or any type of radiation, but we’ve inferred its presence from how it affects objects that we can see. Typically, galaxies are surrounded by clouds of dark matter. Yet astronomers have found that a clump of dark matter located about 2.4 billion light years away appears to be all alone – no galaxies attached. Nearby galaxies collided and are now part of a merging galaxy cluster called Abell 520, but for some reason they left their dark matter behind.
The clump was first detected in 2007 by the Canadian Cluster Comparison Project (CCCP). The CCCP’s findings were reviewed by the Japanese Subaru telescope. Scientists were so puzzled that it was also part of a 2012 investigation by the Hubble Space Telescope, which confirmed that this clump of dark matter has been abandoned. However, additional research by a team at Ohio University found the ratio of dark to normal matter in the cluster to be normal. Clearly, further observations are needed to reveal the exact composition of Abell 520 and figure out how it formed.
