The visible universe actually rests on a structure that we cannot directly observe. This invisible architecture consists of dark matter halos.
A research team from the Andalusian Institute for Astrophysics (IAA-CSIC) and the Canary Islands Institute for Astrophysics (IAC) has carried out the most precise count of these halos spanning the entire history of the universe.
The results were published in the journal Astronomy & Astrophysics Letters.
The research reveals a new theoretical model called GPS. This model works like a positioning system for dark matter.
What exactly was measured?
The resulting data is not a list of individual objects; Something more complex than that: “halo mass function”.
This mathematical tool describes how many dark matter halos exist in each mass range at a particular time in the universe.
Not all halos are the same. Some contain small galaxies. Some include galaxies such as the Milky Way. The largest ones can contain clusters of hundreds or even thousands of galaxies.
Knowing how many of these structures there are and how they have evolved over time is critical to connecting observations with cosmological models.
The models used to date have significant limitations, especially at extreme values of mass.
In the early universe, prediction errors could be as high as 80%.
The new model reduces this difference to 10–20% and provides high accuracy throughout almost all cosmic history.
A model that contains the true complexity of the universe
The key to this progress actually comes from a simple idea: Matter does not gather into perfect spheres.
Dark matter haloes are disordered and complex structures and are shaped by nonlinear gravitational collapses.
To validate the model, the research team compared it to a cosmological simulation called Uchuu. Uchuu, which means “universe” in Japanese, is one of the most comprehensive cosmological simulations ever made.
This simulation, run on the Fugaku supercomputer in Japan, recreates the evolution of the universe in extraordinary detail. The produced catalogs are publicly available in the Skies & Universes database.
Why does this matter now?
Accuracy in counting halos is not just a theoretical exercise.
For example, the James Webb Space Telescope observes very distant galaxies that formed very early in the universe. In order to interpret these data, it is necessary to know how many halos should be present in each period and what mass they are.
Similarly, large sky mapping projects such as DESI aim to reconstruct the large-scale distribution of matter in the universe and understand the nature of dark energy.
With a more accurate model, we can test whether our current theories about the universe—including dark matter and dark energy—actually match observational data.
The GPS model is now available to the international scientific community and can be incorporated into future analyzes and simulations.
An invisible map becoming clearer
Dark matter is still invisible. It does not emit light and cannot be directly detected by radiation.
However, its gravitational effect determines the architecture of the universe.
Making the map of these halos more precise actually means improving the map of the universe itself. This is not just about determining the number of structures; It also means understanding how quickly they emerged and how they shaped the galaxies we see today.
The new “cosmic GPS” does not detect dark matter directly.
But it brings us ever closer to the deep cosmic skeleton that sustains the visible universe.
