According to dark matter theory, dark matter clusters are always closely surrounded by galaxies that are gravitationally attracted to them. However, an exception has been discovered by Myungkook James Jee from the University of California and Andisheh Mahdavi from San Fransisco State University. A dark matter “blob” has been found in the Abell 520 galaxy cluster with much fewer galaxies surrounding it than would be expected if it were formed from a collision. The authors speculate that there may be more than one kind of dark matter, meaning that current dark matter theory needs to be revised.
