The most detailed mapping of dark matter to date has been created by researchers using the ‘gravitational lensing’ effect. Despite making up 85% of the universe and influencing its evolution, dark matter is difficult to detect because it does not interact with light or other forms of electromagnetic radiation, but as far as we know only interacts with gravity.

To find it, researchers working with the Atacama Cosmological Telescope (ACT) in Chile, which will be decommissioned in September 2022 after 15 years of operation, studied the light emitted after the Big Bang, when the universe was only 380,000 years old. . This light is known as the Cosmic Microwave Background (CMB) or “baby picture of the universe” and has traveled for billions of years witnessing the formation of galaxies and stars.

In the dark matter map, orange areas show where there is more mass, purple where there is less or none. The off-white line shows where the light from the dust in our galaxy obscures a deeper image. Credit: ACT Collaboration

The new map uses the CMB light essentially as a backlight to outline all the matter between us and the Big Bang. The research team watched how the gravitational pull of large, heavy structures, including dark matter, warps the CMB on its 14-billion-year journey toward us, the way a magnifying glass bends light as it passes through its lens.

“We made a new mass map using the distortions of light left over from the Big Bang,” says Matthew Madavaseril, an assistant professor in the Department of Physics and Astronomy at the University of Pennsylvania. He adds that the measurements show that both the massive form of the universe and the rate at which it is growing after 14 billion years of evolution are “exactly what one would expect from the standard model of cosmology based on the theory of gravity Einstein”.

The research was presented at a conference at Kyoto University.