Discovery of 'dark dwarf' could open door to decoding dark matter mystery

DNVN - A newly published study shows that mysterious "dark dwarfs" may provide important clues, contributing to clarifying the true nature of dark matter - one of the biggest mysteries of modern cosmology.

A proposed new type of stellar object, called a dark dwarf, may be lurking at the center of our galaxy. These faint, low-mass stars may be powered not by nuclear fusion, but by the annihilation of dark matter particles, potentially revealing the elusive nature of one of the universe’s greatest mysteries. (Artist’s concept). Source: SciTechDaily.

Published in the Journal of Cosmology and Astronuclear Physics, the team of researchers from the UK and Hawaii have introduced the concept of dark dwarfs and described how humans can detect them using existing instruments, including the James Webb Space Telescope. The name “dark dwarfs” is not because they are inherently dark, but because they are intimately linked to dark matter – a matter that remains at the heart of astrophysics and cosmology today.

“We think that 25% of the universe is made up of a type of matter that does not emit light, making it invisible to the naked eye and to telescopes. We can only detect it through its gravitational effects. That’s why we call it dark matter,” explains study co-author Professor Jeremy Sakstein of the University of Hawaii.

Although the existence of dark matter has been confirmed and scientists have observed its behavior, its true nature remains a mystery. Over the past 50 years, many hypotheses have been proposed, but none have been supported by strong experimental data. Research like this one aims to provide practical methods to get closer to a final answer.

Among the most promising candidates for dark matter are Weakly Interacting Massive Particles (WIMPs) – extremely massive particles that interact very weakly with ordinary matter. They pass through everything almost undetected, do not emit light, are not affected by electromagnetic forces, and therefore do not reflect light and remain invisible. WIMPs can only be detected indirectly through their gravitational influence. This is also the type of dark matter necessary for the existence of dark dwarfs.

Illustration of a black dwarf. Source: Image created by Sissa Medialab staff using Adobe Illustrator

“Dark matter can interact gravitationally, so it gets trapped by stars and accumulates inside them. When that happens, it can interact with itself and annihilate itself, releasing energy that heats the star,” Sakstein explains.

Normal stars, like the Sun, shine through nuclear fusion in their cores, when they are massive enough that gravity compresses matter to the point where it triggers reactions between atomic nuclei, releasing enormous amounts of energy that we see as light. Dark dwarfs, on the other hand, also shine, but not through nuclear fusion.

“Dark dwarfs are very small, about 8 percent of the mass of the Sun,” Sakstein said. Such low masses are not enough to start thermonuclear fusion reactions. So these objects, though common in the universe, usually only emit a faint glow from the energy generated by their small gravitational collapses, and are called brown dwarfs.

However, when they exist in regions rich in dark matter, such as the center of the Milky Way, brown dwarfs can transform into other forms. “These objects collect dark matter, making them dark dwarfs,” Sakstein notes. “The more dark matter around them, the more they collect. And the more dark matter they accumulate, the more energy they can generate from their annihilation.”

But all of these theories are valid only for a certain type of dark matter. “For dark dwarfs to exist, dark matter must be made of WIMPs, or any massive particles that can interact with themselves to create visible matter,” Sakstein said. Other theories, such as axions, sterile neutrinos, or faint ultralight particles, are too light to produce the desired effect. Only massive particles that can interact and annihilate themselves into visible energy would provide enough energy to power dark dwarfs.

But for this hypothesis to be valid, a specific method for identifying dark dwarfs is needed. So Sakstein and his colleagues propose a signature: lithium-7. This element burns very quickly in normal stars and quickly disappears. “If you find an object that looks like a dark dwarf, you can check for traces of lithium-7. If it’s still there, it can’t be a brown dwarf or something like that,” Sakstein explains.

Modern instruments such as the James Webb Space Telescope are already thought to be able to detect extremely cold objects such as dark dwarfs. Sakstein, however, suggests a different approach: “Another option is to look at the entire population and then statistically ask whether an additional population of dark dwarfs should be added to better characterize it.”

If scientists identify one or more dark dwarfs in the coming years, would that be enough to support the hypothesis that dark matter is made of WIMPs? “Quite strongly,” Sakstein says. “With light dark matter candidates, like axions, I don’t think we’ll find anything that looks like a dark dwarf. They don’t accumulate inside stars. If we find dark dwarfs, it would be strong evidence that dark matter is massive and interacts strongly with itself but only weakly with the standard model. This includes WIMPs and some exotic models.”

However, he also noted that the discovery of dark dwarfs does not necessarily mean that dark matter is a WIMP, but it could be a WIMP or another form of matter that behaves closely like a WIMP.

If this hypothesis is confirmed, it would open up new research directions, potentially shedding light on one of the universe's greatest mysteries.

La Khe (According to SciTech Daily)

Source: https://doanhnghiepvn.vn/cong-nghe/phat-hien-sao-lun-toi-co-the-mo-canh-cua-giai-ma-bi-an-vat-chat-toi/20250905082132203