Dark matter core challenges theories

The collision of several, massive galaxy clusters has left behind a clump of dark matter, potentially challenging existing theories.

Prevailing theories predict dark matter should stay anchored to galaxies even during the shock of a collision. The observations made by NASA’s Hubble telescope indicate a “dark core” containing far fewer galaxies than would be expected if the dark matter and galaxies were anchored together.

Researchers have proposed a number of explanations for the discrepancy, including the suggestion the dark core contains galaxies that are too dim to be seen by Hubble.