Revealing The Distribution Of Dark Matter In The Early Life Of The Universe For The First Time

Revealing The Distribution Of Dark Matter In The Early Life Of The Universe For The First Time

A Team Of Researchers Used Remnants Of The Cosmic Background Radiation Left Over From The Big Bang To Reveal The Most Ancient Dark Matter Ever Detected.

Scientists have detected dark matter around galaxies that have existed for about 12 billion years. This discovery is the oldest revelation of the mysterious substance that dominates the universe.

In collaboration with researchers at Nagoya University in Japan, recent findings show that dark matter in the early universe was less dense or dense than many current cosmological models predict. Suppose more research works in the future also confirm this theory.

In that case, it will be possible that scientists’ understanding of how galaxies evolve will change and further prove that the fundamental laws governing the universe may have existed in distant times when only 1.7 billion years have passed since the life of the universe, probably there were differences with the current laws governing the universe.

The key to mapping dark matter in the very early universe is the cosmic microwave background (CMB), A type of fossilized radiation from the Big Bang distributed throughout the universe.

Masami Ouchi, a professor at the University of Tokyo, explains in a statement:

Look at dark matter around distant galaxies. Such an idea was crazy. Nobody realized [before] that we could do this. But after I talked about an example of a sizeable distant galaxy, Hironao came to me and suggested that it might be possible to look at the dark matter around these galaxies with the help of the CMB.

Since light takes a finite amount of time to travel from distant objects to Earth, astronomers see other galaxies as when the light left them. The more distant a galaxy is from us, the longer the light travels towards us; therefore, we as observers see them in more distant times. Putting these explanations together, we can conclude that we see the most distant galaxies as they were billions of years ago; These time estimates bring us to a time when the universe was like a toddler compared to its 14.5 billion year life.

Observing dark matter becomes even more complicated and fascinating. Dark matter is a mysterious substance that makes up about 85% of the universe’s total mass. Unlike ordinary cases made of protons and neutrons that make up stars, planets, and our bodies, dark matter does not interact with light. Dark matter does not interact with ordinary matter.

Detection of dark matter from the early universe

We mentioned that dark matter does not interact with light and standard weight; You might ask, this substance interacts with which phenomena are known to humanity? The answer is that to see dark matter, and astronomers must rely on its interaction with gravity.

According to Einstein’s theory of relativity, objects with massive mass cause space-time curvature. A common analogy or example to better understand the subject: is a sheet of elastic rubber holding balls of increasing mass—similarly, the larger the astral body, the more intense the warping of space-time.

Massive objects such as galaxies cause space-time to curve so much that the light emitted from the sources behind those galaxies is curved, Just like when the path of marble is deflected on a rubber pad. This effect changes the position of the light source in the sky, A phenomenon called gravitational convergence.

To study the distribution of dark matter in a galaxy, astronomers can observe how the light emitted from behind a universe changes and passes through the “galaxy acting as a kind of lens” and the widespread phenomenon of gravitational convergence.

The more dark matter the galaxy has in the role of the investigated lens, the greater the distortion of the light passing through it will be. But this technique, despite its usefulness, has limitations.

Since the first and most distant galaxies are very dim, as a result, the more astronomers look into the depths of the universe in more distant times, the effect of convergence and the lens-like role of galaxies will subsequently become more fragile and weaker, and it becomes difficult to see.

On the other hand, scientists need both significant cosmic background sources and many primordial galaxies. It usually limits the dark matter distribution mapping to galaxies about 8 to 10 billion years old.

Relying solely on gravitational convergence and light deflection has limitations.

The CMB is pervasive radiation and was created when the universe cooled enough to form atoms. But the CMB provides a much older source of light than any galaxy. The number of photon-scattering free electrons dwindled in what cosmologists call the “last scattering.” The reduction of free electrons allowed photons to move freely; It means that the world suddenly left the opaque state and took on a transparent shape (allowing light to pass through it) against the light.

On the other hand, the CMB, like other distant light sources in the universe, can be deflected by galaxies containing dark matter due to gravitational convergence.

Yuichi Harikan, an assistant professor at the University of Tokyo, said in a statement:

Most researchers use progenitor galaxies to measure the distribution of dark matter from today to 8 billion years ago. However, we could look further into the past; we used the more distant CMB to measure dark matter.

The team compared the collimated distortions of a large sample of ancient galaxies with those surveyed with the CMB to detect dark matter when the universe was only 1.7 billion years old. The bottom line is that the detected ancient dark matter paints a very different cosmic picture.

According to Harika:

We have measured dark matter from almost the universe’s earliest moments for the first time. Twelve billion years ago, things were very different. [Then] you see more galaxies forming than you do now; The first galaxy clusters have also started to develop.

These clusters can consist of 100 to 1,000 galaxies gravitationally bound to large amounts of dark matter.

Is dark matter a mass?

One of the most critical aspects of the team’s findings is that it raises the possibility that dark matter in the early universe may have been less compact than many current models suggest.

For example, a lambda CDM model, which is also widely accepted in scientific circles, suggests that small CMB fluctuations should lead to gravity, creating dense bundles of matter.

These fluctuations eventually lead to the collapse of matter to form galaxies, stars, and planets and should also lead to the formation of dense pockets of dark matter. Hurricane said:

Our findings are still inconclusive, But if they are authentic, it could indicate a deficiency in all current models as we go back in time and closer to the universe’s early years. It is exciting; Because if the recent result remains valid even after reducing the uncertainties, it could indicate the improvement of the previous models and perhaps give us a better insight into the nature of dark matter.

The research team will continue to collect data.

They want to assess whether the lambda CDM model is consistent with dark matter observations in the early universe. Or it is not, and the assumptions behind this model will need to be revised.

The data used by the team to make the recent findings came from the Subaru Hyper Supreme-Cam Survey; Subaru Hyper analyzes data from a telescope located in Hawaii.

However, researchers have used only one-third of this Data so far. In other words, we can conclude that a better map of the dark matter distribution will be available with the addition of the rest of the observations.

The research team is also looking forward to data from the Vera C. Rubin Observatory’s Legacy Space and Time Survey (LSST), Data that can allow the observation and investigation of dark matter even at times more distant than the last recorded time.

Harikan explains at the end:

LSST allows us to observe half the sky. I see no reason why we cannot know the distribution of dark matter 13 billion years ago.