An illustration showing a halo of dark matter around a spiral galaxy (Image credit: Robert Lea (created with Canva))

New research puts forward compelling new evidence that dark matter interacts with cosmic "ghost particles" called neutrinos. If that is the case, then this interaction could pose a serious challenge for the standard model of cosmology, our current best model of the universe.

Neutrinos earn their spooky nickname due to the fact that as these chargeless and virtually massless particles travel through space at near the speed of light, they barely interact with other particles, ghosting their way through solid objects like planets. In fact, the interactions between these particles and other matter are so rare and fleeting that every second, around 100 trillion neutrinos stream through your body without you feeling a thing. Dark matter is similar; even though it accounts for around 85% of the matter in the universe, whatever comprises dark matter also barely interacts with ordinary matter and light, if at all. In fact, effectively invisible, dark matter can only be inferred due to its interaction with gravity and the effect this has on light and conventional matter.

The evidence for this potentially paradigm-shift-inducing suggestion comes from observations of the universe in its current state, conducted by the Dark Energy Camera on the Victor M. Blanco Telescope in Chile, from galaxy maps created by the Sloan Digital Sky Survey, and details of the universe's distant past gathered by both the Atacama Cosmology Telescope (ACT) and the European Space Agency (ESA) Planck Telescope spacecraft.

These observations have revealed that the modern universe is less "clumpy" than it should be. This cosmic conundrum could be explained by interactions between dark matter and neutrinos, which would impact the way cosmic structures like galaxies form and evolve.

"Our results address a long-standing puzzle in cosmology. Measurements of the early universe predict that cosmic structures should have grown more strongly over time than what we observe today," team member Eleonora Di Valentino of the University of Sheffield said in a statement. “However, observations of the modern universe indicate that matter is slightly less clumped than expected, pointing to a mild mismatch between early- and late-time measurements. This tension does not mean the standard cosmological model is wrong, but it may suggest that it is incomplete.

"Our study shows that interactions between dark matter and neutrinos could help explain this difference, offering new insight into how structure formed in the universe," Di Valentino added.