Shulou(Shulou.com)11/24 Report--

Thanks CTOnews.com netizen Hua Ke high achiever's clue delivery! This article comes from the official account of Wechat: SF Chinese (ID:kexuejiaodian), author: SF

Recently, by analyzing images taken by the James Webb Space Telescope, scientists have determined that three ancient celestial bodies may be so-called "dark stars"-a new type of star driven by dark matter. However, don't let the name deceive you. Scientists believe that these dark stars can be 10 billion times brighter than the sun.

(by Chen Qiang / tr. by Robert Taylor)

Dark matter is a mysterious invisible matter that does not interact with light and other electromagnetic radiation, which makes scientists can only speculate its existence through the gravitational effect of dark matter on visible matter.

Through the observation of the gravitational lens effect, the motion of stars in galaxies and the cosmic microwave background radiation, scientists have found that dark matter exists in galaxies, galaxy clusters and the universe, and its mass is much larger than the total mass of all visible matter in the universe. The latest data show that conventional matter accounts for 4.9% of the composition of the universe, while dark matter accounts for 26.8%, and the remaining 68.3% is dark energy.

Although dark matter plays an important role in the universe, its physical origin remains a mystery. Scientists suspect that dark matter is made up of invisible particles that do not reflect or absorb light, but can produce a gravitational effect. Various experiments around the world are trying to detect this type of particles. Among them, the most promising candidate is called "high mass weakly interacting particle" (WIMP).

With so much dark matter in the universe, will there be stars driven by dark matter?

The first stars in the universe may be dark stars. We know that star formation begins with a molecular cloud, a large chunk of interstellar matter made up of gas and dust. When a region in the molecular cloud collapses under its own gravity, its density and temperature gradually increase until the temperature in the central region is high enough to cause nuclear fusion of hydrogen in the molecular cloud. Nuclear fusion generates heat that prevents the molecular cloud from collapsing further, and a new star is born.

But in 2008, some scientists suggested that the first stars formed in the universe were driven not by hydrogen fusion, but by dark matter annihilation. This kind of star is called "dark star". Their theory is based on the assumption that the antiparticle of a dark matter particle is itself. In this way, when dark matter particles collide with each other, they annihilate and generate heat.

The specific process of dark star formation is like this: in the center of primitive galaxies in the early universe, there will be very dense dark matter clumps and molecular clouds mainly composed of hydrogen and helium; as the molecular clouds cool, it will collapse and absorb dark matter; as the density increases, dark matter particles will annihilate more frequently, generating more and more heat, which will prevent the molecular cloud from collapsing further. At this point, dark stars are formed.

The heat sources of dark stars will be evenly distributed, rather than concentrated in the core like ordinary stars. In addition, unlike ordinary stars, dark stars will continue to accumulate more gas and dark matter, becoming larger and brighter than ordinary stars. If there is enough dark matter, dark stars can grow to millions of times the mass of the sun and more than 10 billion times the brightness of the sun. In this way, if we look at them with telescopes, they look more like galaxies.

Dark stars help solve multiple cosmic puzzles. Recently, a team of scientists analyzed images taken by the James Webb Space Telescope and found that three celestial bodies originally thought to be galaxies are very consistent with the characteristics of dark stars.

The three dark star candidates (JADES-GS-z13-0 JADESmurGSmurz 12-0 and JADES-GS-z11-0) were first identified as galaxies in December 2022. Using spectral analysis, scientists have confirmed that they formed between 320 million and 400 million years after the Big Bang, making them one of the earliest celestial bodies ever observed.

If the discovery of the dark star is confirmed, it will solve a mystery about the evolution of the universe. According to the latest observational data, the earliest galaxies in the universe seem to appear earlier than traditional cosmological models. Most scientists believe that this problem can be solved by making small corrections to the theory. But perhaps these so-called galaxies are just extremely bright dark stars. Because it is obviously faster to form a dark star than to form a galaxy.

When dark stars run out of dark matter, they collapse into black holes, which may be the origin of supermassive black holes at the center of many galaxies. So the existence of dark stars can also explain why there are so many supermassive black holes in the universe.

Most crucially, of course, dark stars help reveal the nature of dark matter. But we don't know whether the antiparticle of a dark matter particle is itself. Even so, it is a question whether stars powered by dark matter annihilation can exist stably. So there are still a lot of doubts about this new discovery.

However, these scientists believe that if the three celestial bodies are dark stars, then their spectra should have unique helium lines. But so far, the James Webb Space Telescope has not been able to give such data. Scientists plan to use the telescope to make further observations of them in the near future.

References:

Https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.100.051101

Https://doi.org/10.1073/pnas.2305762120

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.