Bennington College Physicist Reveals New Clues to the Shape-Shifting Dance of Dark Matter and Black Holes
A new study by physicist and visiting faculty member Dor Ben-Amotz '76, accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS), sheds new light on what dark matter is made of—and suggests that some of the universe's smallest galaxies may be hiding massive black holes at their centers.
The paper, "Shape Shifting Light Dark Matter Solitons," examines a leading alternative to standard dark matter theory, in which dark matter behaves like a quantum wave rather than a swarm of particles. In this model, galaxies contain a dense pool of dark matter called a soliton. Ben-Amotz developed new mathematical formulas showing how that shape of the soliton shifts and sharpens when a black hole sits at a galaxy's center.
Applying these tools to 23 dwarf spheroidal and 25 ultra-faint dwarf galaxies, Ben-Amotz compared two competing explanations for patterns in their stellar motion: one where these two types of galaxies contain dark matter particles of different masses, and another where all the galaxies share a single particle mass, plus shape-shifting black holes. A detailed look at two galaxies—Draco and Segue I—supported this second possibility, predicting a central black hole in Segue I of roughly 400,000 solar masses, consistent with independent findings by other researchers.
"These results demonstrate the utility of soliton shape-shifting predictions in constraining dwarf galaxy dark matter profiles and revealing the possible presence of central black holes," the study concludes. The paper has been accepted for publication in MNRAS and will appear online in the coming weeks, at which point it will be assigned a DOI. A plain-language summary of the research is available via Gist Science. The preprint is also available on arXiv (arXiv:2506.01282).arxiv