They create “cosmic GPS” that reveals the most precise invisible map of the universe

Grenade. A team of cosmologists from the Institute of Astrophysics of Andalusia (IAA-CSIC) and the Institute of Astrophysics of the Canary Islands (IAC) has obtained the most precise census to date of dark matter halos in the universe.

These invisible structures surround galaxies and galaxy clusters; They are concentrations of matter that does not emit light nor can be directly observed, but whose gravity holds galaxies together and guides their formation, acting as the “scaffolding” of the universe.

The study led by the Institute of Astrophysics of Andalusia (IAA-CSIC) and the Institute of Astrophysics of the Canary Islands (IAC) has achieved the most precise census to date of these structures throughout the 13.8 billion years of history.

This record, which cosmologists call the “halo mass function,” is not an individual list of objects, but rather a mathematical description that indicates how many dark matter halos exist in each mass range at a given time in the universe.

“This is important because not all haloes are the same: some host very small galaxies; others galaxies like the Milky Way; and the most massive ones can bring together enormous clusters with hundreds or thousands of galaxies,” explains Elena Fernández García, researcher at the IAA-CSIC and first author of the article, published in the journal Astronomy & Astrophysics Letters.

This new result is based on the development of a theoretical model called GPS+, which allows us to predict with great precision the abundance of dark matter halos at different stages in the history of the universe.

The work corrects limitations of previous approaches, which could deviate by up to 80 percent when describing the early universe.

The new model reduces these discrepancies, especially at the mass extremes – where the uncertainties were greatest – to around 10-20 percent, maintaining high precision throughout almost all of cosmic history.

“Having a more accurate census of dark matter halos is key to connecting these observations with theoretical models and checking whether our description of the universe – including the nature of dark matter and energy – fits the data,” says Elena Fernández.