Long-held assumptions about what lies at the center of the Milky Way could be incorrect, as new international research suggests dark matter, instead of a supermassive black hole, may reside in the heart of the galaxy.
Astronomers say that a large cache of dark matter may be responsible for the gravitational pull long attributed to a supermassive black hole named Sagittarius A* (Sgr A*). According to a recent paper published in the Monthly Notices of the Royal Astronomical Society, the invisible, entirely theoretical substance called dark matter could explain the observed motion of a group of stellar bodies known as S-stars, which reside light-years from the galactic center.
Dark Matter and the Milky Way
The international team concluded that fermionic dark matter, a type of light subatomic particle, could provide a unique structure that accounts for existing observations of the Milky Way’s core. That structure would be a single entity composed of two elements: a super-dense, compact core and an immense halo. The team notes that the dense core would produce a gravitational pull similar to that expected of a black hole, which would explain the S-stars’ orbits.
A precise mapping of the rotational curve of the Milky Way’s outer halo, completed by the European Space Agency’s GAIA DR3 mission, provided essential data to the team, recording how stars and gas orbit the galaxy’s edge.
The Keplerian decline, a phenomenon in which the galaxy’s rotational curve slows down as objects are further away from the galaxy’s central mass, was also discernible in the data. The team believes this reflects the intersection between the outer halo of their unique dark matter model, paired with more traditional ideas involving the presence of ordinary matter.
Revising Our Perspectives on the Milky Way
According to the researchers, this deviation supports their fermionic model of dark matter over the traditional Cold Dark Matter model, adding that Cold Dark Matter halos are spread out with long tails, while fermionic dark matter is much more compact.
“This is the first time a dark matter model has successfully bridged these vastly different scales and various object orbits, including modern rotation curve and central stars data,” said study co-author Dr Carlos Argüelles, of the Institute of Astrophysics La Plata. “We are not just replacing the black hole with a dark object; we are proposing that the supermassive central object and the galaxy’s dark matter halo are two manifestations of the same, continuous substance.”
The team cites an earlier study by Pelle et al., published in the Monthly Notices of the Royal Astronomical Society, which provides some support for their work. According to the earlier study, accretion disks illuminating dense dark matter cores should cast a shadow-like feature reminiscent of one captured by the Event Horizon Telescope collaboration when attempting to view Sgr A*.
“This is a pivotal point,” said lead author Valentina Crespi, of the Institute of Astrophysics La Plata. “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.”
A Unified Approach
After conducting a statistical comparison between their new fermionic dark matter model and the traditional black hole model, the team concluded that current stellar data do not yet support one model over the other. However, the fermionic model provides a unified framework for both the galactic center and the galaxy as a whole, which is promising.
More data will be required to further investigate this fermionic dark matter model. The team is hopeful that Chile’s Very Large Telescope, with its GRAVITY interferometer, will provide that data. The team will be looking for photon rings, a feature of the black hole model but not of the fermion dark matter model. If the team’s fermionic model proves to be correct, it could hold the promise for a radical reshaping of how astronomers understand our galaxy.
The paper, “The Dynamics of S-stars and G-sources Orbiting a Supermassive Compact Object Made of Fermionic Dark Matter,” appeared in Monthly Notices of the Royal Astronomical Society on February 5, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.