Dark matter may not be a single thing

This composite image captured using NASA’s Hubble Space Telescope and Chandra X-ray Observatory and the ground-based Giant Magellan Telescope shows the Bullet Cluster, a pair of galaxy clusters that collided. Normal matter is shown in the cluster in pink, while gravitational lensing reveals dark matter in the cluster shown in blue. This observation has provided one of the clearest direct examples of dark matter. X-ray: NASA/CXC/CfA/M.Markevitch, Optical and lensing map: NASA/STScI, Magellan/U.Arizona/D.Clowe, Lensing map: ESO WFI

doi.org/10.1016/j.scib.2026.01.077
Credibility: 989
#Dark Matter

Dark matter is one of the great enigmas of the Universe

It neither emits, absorbs, nor reflects light, but it exerts a strong gravitational influence that helps form and maintain galaxies, as well as bending light from distant objects.

For decades, scientists have worked with the “cold dark matter” model, which imagines heavy, slow-moving particles interacting only through gravity.

This model successfully explains many cosmic observations, but more recent, precise data reveal problems it cannot completely solve.

In some dwarf galaxies, dark matter appears more “diffuse” than expected, with lower density at the center.

At the same time, observations of strong gravitational lenses show extremely compact and dense clusters of dark matter, much more concentrated than traditional predictions indicate.

These differences create a puzzle that is difficult to fit into a single explanation.

Now, a recent study by researchers at the Purple Mountain Observatory of the Chinese Academy of Sciences proposes an interesting solution: dark matter may not be made of a single type of particle, but of at least two, with different masses.

They suggest a model called “two-component self-interacting dark matter.” In this scenario, heavier and lighter particles are not limited to attracting each other through gravity: they also collide directly with each other.

Over time, a process similar to what happens in star clusters occurs, called mass segregation.

The heavier particles migrate to the center of galaxies, while the lighter ones spread to the outer regions.

High-resolution simulations and theoretical analyses have shown that this mechanism can explain the seemingly contradictory observations.

In smaller and fainter galaxies, it creates nuclei with lower density at the center, matching what telescopes see.

In denser environments, it forms very compact regions capable of producing strong gravitational lenses.

Furthermore, the model increases the probability of small-scale lensing events, helping to resolve another discrepancy: observations indicate more small structures acting as “lenses” than the traditional model predicted.

The authors believe that several small-scale anomalies, which seemed conflicting, may actually be signs that dark matter has a more complex internal behavior than we imagined.

With advances in astronomical research and gravitational lensing measurements, it will be possible to test whether dark matter truly has multiple components.

This work, published in the journal Science Bulletin, represents another step towards better understanding the hidden nature of most of the matter in the Universe.

Published in 03/29/2026 00h38

Portuguese version

Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.

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