Dark Dwarfs May Reveal True Nature of Dark Matter

Black dwarfs are hypothetical objects fed by dark matter that have been formed from the cooling of brown dwarfs, according to a team of astronomers from the University of Durham, the University of Hawaii and the University of Liverpool.

An impression of a dark dwarf. Image credit: Gemini AI.

What we know today about dark matter is that it exists and how it behaves – but not yet what it is.

Over the past fifty years, several hypotheses have been proposed, but none has yet gathered enough experimental evidence to prevail.

Among the most known black matter candidates are the massive particles weakly in interaction (WIMP) – very massive particles which interact very weakly with ordinary matter: they go through unnoticed things, do not emit light and do not respond to electromagnetic forces and are only revealed by their gravitational effects.

This type of dark matter would be necessary for dark dwarfs to exist.

“The dark matter interacts gravitally, it could therefore be captured by stars and accumulate inside,” said the professor at the University of Hawaii, Jeremy Sakstein.

“If this happens, he could also interact with himself and destroy, releasing energy that heats the star.”

Ordinary stars shine because nuclear fusion processes occur in their nuclei, generating large amounts of heat and energy.

The merger occurs when the mass of a star is large enough for gravitational forces to compress the material towards the center with such intensity that they trigger reactions between atomic nuclei.

This process releases an enormous amount of energy, which we consider a light. The dark dwarves also emit light – but not because of nuclear fusion.

“Black dwarfs are very low mass objects, about 8% of the mass of the sun,” said Professor Sakstein.

“Such a small mass is not sufficient to trigger fusion reactions.”

“For this reason, such objects – although very common in the universe – generally emit only a small light and are known to scientists under the name of brown dwarfs.

However, if the brown dwarfs are located in regions where dark matter is particularly abundant – like the center of our Milky Way Galaxy – they can turn into something else.

“These objects collect the dark matter which helps them to become a dark dwarf,” said Professor Sakstein.

“The more dark matter you have, the more you can capture.”

“And the more dark matter is found inside the star, the more energy there will be thanks to its annihilation.”

“For black dwarves to exist, dark matter must be made of Wimp, or any heavy particle that interacts with itself to produce visible matter.”

“Other candidates proposed to explain dark matter – such as axes, blurred ultra -light particles or sterile neutrinos – are too light to produce the expected effect in these objects.”

“Only massive particles, capable of interacting with each other and annihilation with visible energy, could feed a dark dwarf.”

However, this whole hypothesis would have little value if there was no concrete way to identify a dark dwarf.

For this reason, Professor Sakstein and his colleagues offer a distinctive marker.

“There were a few markers, but we suggest lithium-7 because it would really be a unique effect,” said Professor Sakstein.

“Lithium-7 burns very easily and is quickly consumed in ordinary stars.”

“So, if you could find an object that looked like a dark dwarf, you can seek the presence of this lithium because it would not be there if it was a brown dwarf or a similar object.”

The team’s work appears in the Journal of Cosmology and Astroparticle Physics.

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Djuna Croon and al. 2025. Black dwarfs: Dark propulsion under-species awaiting discovery at the Galactic Center. Jcap 07: 019; DOI: 10.1088 / 1475-7516 / 2025/07/019