Despite making up roughly 85% of all matter in the universe, the fundamental nature of dark matter (DM) still eludes scientists. Thus far, no experiment has been able to determine what dark matter is made of.
One way scientists are probing for DM is by looking at the production of ordinary particles when two DM particles crash into each other and annihilate or the disintegration of a DM particle into other particles. It is thought that such processes take place in regions of the universe where DM particles are densely packed by gravity, most notably the Galactic Center at the heart of the Milky Way.
In a study submitted to Physical Review D, the IceCube Collaboration presents a search for neutrinos from DM annihilation using nine years of data taken with IceCube’s DeepCore detector, a subdetector that is sensitive to lower-energy neutrinos. A significant excess of neutrinos was not found, and new limits were set on DM interactions.
Since DeepCore is optimized to detect neutrinos in the lower-energy, GeV, range, researchers found it was ideal for searching for DM particles with masses in the same energy scale. They built a statistical model to see whether the data looked more like a uniform background (no DM signal) or an excess of neutrinos coming from the direction of the Galactic Center (DM signal).
To improve the sensitivity of the search, they also included information about the neutrino energies and types. If the researchers saw a spherical clustering of neutrinos coming from the direction of the Galactic Center, then that could indicate DM interactions.
“Our results are complementary to other types of DM searches, such as those using underground detectors or gamma-ray telescopes,” says Thien Nhan Chau, a postdoctoral researcher at Université Libre de Bruxelles who led the study. “In fact, for some dark matter scenarios, our limits are currently world leading. These new constraints help theorists refine their models by ruling out regions of the DM parameter space that are not consistent with experimental results.”
The next step will be to extend this type of analysis to higher energies, especially since the IceCube Collaboration has already detected high-energy neutrinos from the Milky Way. Furthermore, the IceCube Upgrade will enhance the IceCube detector’s sensitivity at lower energies, which will improve the researchers’ ability to probe DM signals.
For Chau, “it’s exciting to think that neutrinos, which once played a key role in shaping our understanding of the Standard Model of particle physics, can now also help us explore new physics beyond it and perhaps even reveal the nature of DM.”
+ info “Search for GeV-scale Dark Matter from the Galactic Center with IceCube-DeepCore,” IceCube Collaboration: R. Abbasi et al. Submitted to Physical Review D. arxiv.org/abs/2511.00918