Its age is 12 billion years.
Scientists discovered dark matter surrounding the galaxy, which existed already 12 billion years ago. According to Space.com, this is the earliest known evidence of the existence of this mysterious substance.
Also read: First color photo of the early universe taken by the James Webb Space Telescope – NASA
This discovery indicated to scientists that dark matter in the early universe was less “lumpy” than most current cosmological theories predict. If further observations confirm this assumption, it could change our understanding of how galaxies form and evolve. In addition, the discovery may indicate that the fundamental laws governing the development of the cosmos may have been different in the “infancy” of the universe.
The key to mapping dark matter in the early universe is the cosmic microwave background (CMF), a kind of fossil radiation left over from the Big Bang that spreads throughout space.
Because light takes time to reach Earth, astronomers see galaxies as they were when the light left them. The more distant the galaxy, the longer its light travels to us, accordingly, the further in time we see it. That is, the most distant galaxies of the universe are observed as they were billions of years ago.
Observing dark matter is even more difficult. It is believed to make up 85% of the total mass of the universe, but does not interact with matter and light like normal matter. In order to see it, astronomers rely on the gravitational influence of dark matter on other objects.
Relic radiation is an earlier source of light than any galaxy. It arose when the universe cooled enough to allow atoms to form, reducing the number of free electrons that scatter photons, in what cosmologists call the last scattering. The decrease in the number of free electrons allowed photons to travel freely, meaning that the universe suddenly stopped being opaque and became transparent to light.
And just like light from other distant sources, the relic radiation can be distorted by galaxies with by dark matter due to gravitational lensing.
In the course of the study, scientists combined the lensing distortions of a large sample of ancient galaxies with the distortions of relic radiation, which allowed us to detect dark matter that existed when the universe was only 1.7 billion years old.
“For the first time, we have measured dark matter almost from the earliest moments of the universe. 12 billion years ago, things were completely different. You see more galaxies in the process of formation than you do now; the first clusters of galaxies are also beginning to form,” said one of the scientists, Yuichi Harikane.
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