A research team from Durham University, the University of Hawaii, and the University of Liverpool suggests that dark dwarfs are theoretical objects driven by dark matter, created from the cooling process of brown dwarfs.
Currently, we understand that dark matter exists and how it behaves, but we are still unsure of its true nature.
In the last half-century, various theories have emerged, but gathering sufficient experimental evidence remains a challenge.
Some of the most well-known candidates for dark matter include weakly interacting massive particles (WIMPS), which are substantial particles that interact very slightly with ordinary matter. They pass through unnoticed, do not emit light, and reveal themselves only through gravitational effects.
This form of dark matter is essential for the existence of dark dwarfs.
“Dark matter interacts with gravity, allowing it to be captured by stars and accumulate within them,” explained Professor Jeremy Sachstein from the University of Hawaii.
“If this occurs, it may also interact internally, leading to annihilation and energy release that heats the star.”
A nuclear fusion process occurs at the star’s core, generating significant heat and energy, which allows a typical star to shine.
Fusion happens when a star’s mass is sufficient for gravity to compress matter toward the center intensely enough to initiate reactions between the nuclei.
This process releases a tremendous amount of energy, which is perceived as light. Although dark dwarfs also emit light, they do not do so through nuclear fusion.
“Dark dwarfs are low-mass objects, roughly 8% of the solar mass,” noted Professor Sachstein.
“Such small masses are insufficient to trigger a fusion reaction.”
“Consequently, these objects are prevalent in the universe but typically emit only dim light, being classified as brown dwarfs by scientists.
However, if brown dwarfs reside in regions with a high concentration of dark matter (such as the center of the Milky Way), they can evolve into different entities.
“These objects gather dark matter that enables them to transform into dark stars,” Professor Sachstein stated.
“The greater the surrounding dark matter, the more can be captured.”
“And as the dark material accumulates within the star, more energy is generated through its annihilation.”
“For a dark dwarf to exist, dark matter must consist of heavy particles that engage strongly with one another to produce visible matter.”
“Alternative candidates proposed to explain dark matter, such as axions, ambiguous ultralight particles, or sterile neutrinos, are too light to yield the expected effects on these objects.”
“Only massive particles capable of interacting with each other and annihilating to produce visible energy can facilitate the emergence of dark dwarfs.”
However, this hypothesis lacks substantial value without a definitive method of identifying dark dwarfs.
Therefore, Professor Sachstein and his team have suggested distinctive markers.
“There were a few indicators, but lithium-7 presents a unique scenario,” Professor Sachstein mentioned.
“Lithium-7 combusts readily and is rapidly depleted in regular stars.”
“Thus, if you identify an object resembling a dark dwarf, you should search for the presence of lithium, as it would be absent if it were a brown dwarf or something similar.”
The team’s study will be published in Journal of Cosmology and Astroparticle Physics.
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DJUNA CROON et al. 2025. Dark Dwarf: A theoretical dark matter-driven star-like object awaiting discovery at the Galactic Center. jcap 07:019; doi:10.1088/1475-7516/2025/07/019
Source: www.sci.news
