Dark matter was mapped with record precision

The universe the most accurate map ever made of the distribution of the dominant dark matter. Researcher at Aalto University Ghassem Gozaliasl was involved in the US space agency NASA research that created the map.

Based on the map, it seems that dark and so-called ordinary matter have grown together.

It is difficult to make observations of dark matter. It does not radiate or send any other direct signals of itself, but it obeys gravity nonetheless. With its help, dark matter can be observed indirectly.

There is five times more dark matter compared to normal matter, which is what everything around us is made of. Ordinary matter makes up about five percent of the matter in the universe, while dark matter makes up about 27 percent.

The study was published Nature Astronomy in the journal.

Map was born from only a small part of the starry sky. The target was the region of the constellation Sextant, which covers an area in the sky the size of about 2.5 full moons.

The researchers observed this region with several telescopes for more than 250 hours. For example, the James Webb space telescope was used in the study.

Almost 800,000 galaxies were detected in the area. That’s about ten times more than there are already galaxies on Earth observatory maps.

The amount is also double compared to the map of NASA’s older space telescope, Hubble.

Recent research shows how dark matter overlaps and intertwines with ordinary matter.

For example, the map shows how galaxy clusters contain huge amounts of dark matter. The same dark matter is also present in the strands of visible matter that connect clusters of galaxies to each other.

“The map confirms that dark matter behaves exactly as cosmological models predict. It obeys gravity and creates gravitational fields like normal matter,” says Gozaliasl.

Dark matter was searched for by observing how its mass curves space and bends the light coming from distant galaxies. At that time, the light of the galaxies arrives as if through a distorting lens.

Based on research, galaxy clusters and masses can be thought of as cosmic villages and cities surrounded by an invisible bubble of dark matter. These groupings and masses are connected by highways formed by threads in the cosmic web.

As a purpose was to measure the position of ordinary matter and compare it to the position of dark matter.

As dark matter clouds move away from the centers of galaxy clusters, they become rarer. The dark matter structures mapped by Gozaliasl’s group were millions of light years across.

“They are not so spherical and precise in diameter. They are more like haze, which is thicker in some places and thinner in others,” Gozaliasl describes.

The research made extensive use of artificial intelligence, which is capable of automatically detecting and classifying objects from millions of images.

Map shows that dark and ordinary matter have grown together, says Durham University astrophysicist Richard Massey in Aalto’s press release.

At the beginning of the universe, ordinary matter and dark matter were probably more evenly distributed than today. After that, the dark matter accumulated first and its clumps pulled the ordinary matter together.

Regions were created with enough matter to form stars, galaxies and eventually planets.

“Light from distant galaxies has been traveling towards us for billions of years. We get to see the universe when it was young, watch how dark matter shaped everything and how the galaxies found their place in this cosmic dance,” Gozaliasl describes.

“The whole story of humanity is just one brief moment in this story that is billions of years old.”