The IceCube Neutrino Observatory, embedded in a cubic kilometer of Antarctic ice, searches for weakly interacting particles called neutrinos that are able to travel undisturbed through the cosmos. Of interest are high-energy astrophysical neutrinos that can arise from cosmic ray interactions with matter or photons in astrophysical sources. So far, high-energy neutrino emission has been observed from a few specific sources, but these can only be attributed to a small percent of the total number of astrophysical neutrinos observed by IceCube.
One possible explanation for this is that neutrino sources are faint and numerous, each contributing only a small number of neutrinos. Like galaxies, neutrino sources are thought to live in regions of space where large-scale matter distribution is denser than average, so the extragalactic neutrinos may, on average, be spatially correlated with galaxies.
In a paper recently submitted to The Astrophysical Journal, the IceCube Collaboration presents a search for clustering between a catalog of galaxies and 10 years of IceCube data using a tool referred to as the two-point angular cross-correlation. They did not find any significant clustering between the galaxies and neutrinos.
Widely used in cosmological studies, the two-point angular cross-correlation function can be used to measure the degree of clustering between two astrophysical populations, in this case the galaxies and neutrinos. The galaxy catalog was assembled using infrared sources observed by the Wide-Field Infrared Survey Explorer and the Two Micron All-Sky Survey, and traces the large-scale matter distribution up to a distance of about 3600 light years.
“Our results suggest that the neutrinos are coming from more distant sources that are outside of the volume explored by the infrared galaxy catalog or that neutrinos are not correlated with large-scale matter distribution,” says David Guevel, who co-led the study as a PhD student at the University of Wisconsin–Madison. Guevel is now a postdoctoral researcher at Michigan Technological University.
With the planned IceCube-Gen2 extension, the larger volume will allow researchers to identify distant, faint neutrino sources more effectively.
+ info “Constraints on the Correlation of IceCube Neutrinos with Tracers of Large-Scale Structure,” IceCube Collaboration: R. Abbasi et al. Submitted to The Astrophysical Journal. arxiv.org/abs/2510.18119