February 19, 2026 

For decades, the accepted wisdom has been that at the heart of our Milky Way galaxy lurks a supermassive black hole known as Sagittarius A (Sgr A), a gravitational monster with the mass of 4 million suns. However, a dramatic new study published today is challenging this fundamental tenet of modern astrophysics, proposing that the Milky Way may not have a supermassive black hole at its centre at all. Instead, an international team of researchers suggests that the galactic nucleus is actually an enormous, dense clump of a very specific kind of dark matter .

This radical hypothesis, appearing in the Monthly Notices of the Royal Astronomical Society, doesn’t deny that something incredibly massive exists at the galaxy’s core. The evidence for that is overwhelming, primarily from the breathless orbits of the so-called S-stars, a group of stars that whip around the galactic centre at speeds of several thousand kilometres per second. Their trajectories have long been used to calculate the mass of the central object, estimated at roughly 4.3 million solar masses . The cleanest, most parsimonious explanation has always been a black hole, a conclusion seemingly confirmed in 2022 when the Event Horizon Telescope (EHT) collaboration captured a historic image of Sgr A*, revealing a dark shadow framed by a bright ring of glowing gas .

The new research, led by astrophysicist Valentina Crespi of the Institute of Astrophysics La Plata in Argentina, argues that this evidence can be reinterpreted. The team proposes that the central object is not a singularity cloaked by an event horizon, but a core of fermionic dark matter. Fermions are subatomic particles that obey the Pauli exclusion principle, which prevents them from occupying the same quantum state. This property would stop the dark matter from collapsing into an infinitely dense point, but it could still allow it to form an ultradense, gravitationally stable blob—a kind of dark matter “core” surrounded by a more diffuse dark matter halo .

This single, continuous structure is the key to the theory’s appeal. It elegantly bridges two cosmic scales that have traditionally required separate explanations. The hyper-dense inner core mimics the gravitational pull of a black hole, perfectly explaining the frantic dance of the S-stars. Simultaneously, the extended dark matter halo accounts for the larger-scale rotation of the entire galaxy, particularly the Keplerian decline—a slowdown in rotational speed at the galaxy’s outskirts—recently mapped in precise detail by the European Space Agency’s Gaia mission . “We are not just replacing the black hole with a dark object,” explains study co-author Dr. Carlos Argüelles, also of the Institute of Astrophysics La Plata. “We are proposing that the supermassive central object and the galaxy’s dark matter halo are two manifestations of the same, continuous substance” .

Perhaps the most stunning claim is that this model is also consistent with the iconic 2022 EHT image. A previous study had already demonstrated that when an accretion disk of hot gas illuminates a dense dark matter core, the intense bending of light creates a central shadow surrounded by a bright ring, almost identical to the signature expected from a black hole . “This is a pivotal point,” says lead author Crespi. “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” .

The researchers are not claiming to have disproven the existence of the black hole. Instead, they have shown that a dark matter core is a physically possible and, in some ways, more unified explanation. When they statistically modeled the orbit of the star S2—the closest and most carefully observed S-star—they found that the trajectories predicted by the black hole model and their fermionic dark matter model differed by less than one percent . Current observational technology simply cannot distinguish between them.

So, how can astronomers ever settle the question? The answer lies in future, more precise observations. A key difference between the two scenarios is the predicted existence of photon rings. According to general relativity, the extreme gravity around a black hole’s event horizon should create a series of nested rings of light—a distinct signature that would be absent around a dark matter core, which lacks a singularity and an event horizon . While one research group has previously claimed to have detected such a ring, the finding was met with significant skepticism from the wider scientific community .

The coming years promise to be a golden age for testing this hypothesis. Instruments like the GRAVITY interferometer on the Very Large Telescope in Chile, which can track stars with extraordinary precision, will be crucial. Future, more sensitive observations by the Event Horizon Telescope could also look for the tell-tale photon ring signature. For now, the true nature of the beast at the centre of our galaxy remains an open, thrilling question. Whether it is an elusive dark matter core or the supermassive black hole we’ve always imagined, the quest to understand it is forcing scientists to re-examine the very fabric of our cosmic home.”