Substructure maps provide compelling evidence for the presence of dark matter clumps within galaxies. By analyzing the motions of stars and gas in galaxies, astronomers can create maps that reveal the distribution of mass within these systems. These maps often show the presence of substructures, such as satellite galaxies, stellar streams, and gas clouds, that are not directly visible but still exert a gravitational influence on surrounding matter.

The existence of these substructures suggests that dark matter is not smoothly distributed throughout galaxies but instead forms distinct clumps or halos. This clumpy distribution of dark matter is consistent with predictions from simulations of galaxy formation and evolution and provides further support for the existence of this mysterious form of matter.