An international group of astrophysicists has provided the most direct evidence that dark matter is not composed of supermassive particles. The study, based on supercomputer simulations, suggests dark matter is replacing it. axis — Hypothetical particles are so light that they travel like waves in space. If true, it could not only reveal what makes up 85% of the matter in the universe, but also lead to new physics beyond the Standard Model. Study published Nature Astronomy.

Dark matter is difficult to study because it does not emit, absorb, or reflect light. Instead, a team led by PhD student Alfred Amrut (University of Hong Kong) investigated the material’s effect on humans. gravity lens.

In this effect, the galaxy and its huge halo of dark matter warp the fabric of space-time around it. Light from a more distant source follows this curvature and bends around the galaxy as if passing through a lens.

When the foreground lens and the distant light source are close together, astronomers see multiple images of the same background object. The position and brightness of these images depend on the distribution of dark matter in the lens, providing powerful exploration of mysterious matter.

For the past two decades, astrophysicists have been trying to accurately reproduce the position and brightness of these few images because they assumed that dark matter consists of weakly interacting massive particles (WIMPs). If WIMPS is dark matter, the density of galaxies should decrease smoothly as you move away from the centre. Other than that, astronomers actually infer from images obtained in lenses.

Instead, Amrut’s team turned to an alternative candidate for dark matter: the axes. These ultralight particles were first proposed in the 1970s to solve the particle physics problem of the strong force. Quantum theory says that axes move in space as waves, not particles, causing random density fluctuations as the waves interact with each other. These random fluctuations would make the distribution of dark matter across the galaxy uneven. (It should be noted that neither WIMPs nor axons were directly detected.)

Assuming that dark matter consists of axes, Amrut and colleagues were able to reproduce the observed positions and luminosities of the four lens system HS 0810+2554: a foreground elliptical galaxy that splits light from the background galaxy into four images.

“We’ve reached a point where the current dark matter paradigm needs to be revised,” says Amrut. “It may not be easy to say goodbye to supermassive particles, long heralded as favorite candidates for dark matter, but evidence is accumulating that dark matter has the wave-like properties of ultralight particles.”

However, Edward Hardy (University of Liverpool, UK), who was not involved in the research, urges caution. “This paper is just a first step, and much more analysis is needed to determine the nature of dark matter,” he says. According to team member George Smoot, the James Webb Space Telescope should explore many more systems with gravitational lenses, which should enable more rigorous testing of the idea.

If this future work solidifies the findings of Amrut’s research, Hardy says it will be a surprising discovery. “This will have important implications not just for astrophysics, but for high-energy particle physics in general,” he says.