Astronomers are now challenging the long-held belief that a supermassive black hole sits at the heart of our Milky Way galaxy. New research, published in the scientific journal Monthly Notices of the Royal Astronomical Society in February 2026, suggests that an enormous, ultra-dense concentration of dark matter could be responsible for the powerful gravitational effects observed at the galaxy’s core. This invisible substance, which makes up most of the universe's mass, might explain both the rapid movement of stars near the center and the broader rotation of the galaxy.
A New Theory for the Galactic Core
For decades, scientists have believed that Sagittarius A (Sgr A), a compact radio source with a mass 4.3 million times that of our Sun, is a supermassive black hole. This black hole was thought to explain the extreme orbits of a group of stars known as S-stars, which race around the galactic center at speeds of several thousand kilometers per second. However, an international team of researchers, including Dr. Valentina Crespi from the Institute of Astrophysics La Plata, has proposed an alternative. They suggest that a specific type of dark matter, made of light subatomic particles called fermions, could form a unique cosmic structure that fits these observations.[sciencedaily+3]
This new model describes a single, continuous system made of dark matter. It features a super-dense, compact core surrounded by a vast, diffuse halo. The inner core is so massive and concentrated that it could mimic the gravitational pull of a black hole. This gravitational mimicry would explain the observed paths of the fast-moving S-stars and other dust-covered objects called G-sources near the galactic center.[sciencedaily+2]
Explaining Galaxy-Wide Rotation
Beyond the immediate galactic center, the dark matter model also provides an explanation for the movement of stars and gas across the Milky Way's vast outer regions. The broader, more diffuse halo of this fermionic dark matter structure shapes the galaxy's outer motion. This is consistent with new data from the European Space Agency's GAIA DR3 mission, which precisely mapped how stars and gas move in the Milky Way's outer halo.[sciencedaily+1]
The GAIA DR3 data show a slowdown in orbital speeds at great distances from the center, a pattern known as the Keplerian decline. Researchers say this observation aligns well with the predictions of their dark matter halo model, especially when combined with the known mass of the Milky Way's disk and central bulge. This marks the first time a dark matter model has successfully connected the dynamics of both the central stars and the large-scale rotation of the galaxy.[thedebrief+6]
The "Black Hole Shadow" Puzzle
One of the most compelling pieces of evidence for Sagittarius A* being a black hole came in 2022. The Event Horizon Telescope (EHT) collaboration captured an image of a "shadow" at the Milky Way's center, which was consistent with theoretical predictions for a black hole. However, the new dark matter theory can also account for this iconic image.[universemagazine]
A previous study by Pelle and collaborators in 2024, also published in Monthly Notices of the Royal Astronomical Society, showed that a dense dark matter core, when illuminated by an accretion disk, could cast a shadow-like feature strikingly similar to the EHT image. Dr. Valentina Crespi emphasized this consistency, stating, "Our model not only explains the orbits of stars and the galaxy's rotation but is also consistent with the famous 'black hole shadow' image. The dense dark matter core can mimic the shadow because it bends light so strongly, creating a central darkness surrounded by a bright ring." This dual success, both in explaining stellar dynamics and the visual appearance of the galactic center, strengthens the case for the fermionic dark matter interpretation.[universemagazine+6]
What Comes Next for Research
This groundbreaking study opens new avenues for understanding the fundamental nature of our galaxy's core. While current data for the inner stars cannot yet definitively distinguish between a supermassive black hole and a dark matter core, the new model offers a unified framework for the galactic center and the galaxy at large.
Future observations will be crucial to test this theory further. Researchers will look for more precise data from advanced instruments, such as the GRAVITY interferometer on the Very Large Telescope in Chile. Scientists will also search for unique "photon rings," which are a key signature of black holes but would be absent in the dark matter core scenario. The outcome of these future investigations could significantly reshape our understanding of the cosmic behemoth at the heart of the Milky Way.[earthsky+2]
