Dark Matter May Replace Black Hole at Milky Way's Heart

A Radical Challenge to Black Hole Theory

Astronomers have proposed a bold alternative to one of the most widely accepted ideas in modern astrophysics: that a supermassive black hole sits at the centre of our galaxy. A new study, published on the fifth of February twenty twenty-six in Monthly Notices of the Royal Astronomical Society, suggests that a massive concentration of dark matter made from subatomic particles called fermions could be responsible for the gravitational forces previously attributed to Sagittarius A star.

A Unified Framework

The international research team, led by Valentina Crespi from Argentina's Institute of Astrophysics La Plata, has developed a model in which fermionic dark matter naturally forms a super-dense core surrounded by a vast, diffuse halo. This is the first time a dark matter model has successfully connected observations at dramatically different scales, from stars racing around the galactic centre at thousands of kilometres per second to the gentle rotation of matter in the Milky Way's outer reaches.

The model accounts for the orbits of S-stars, a cluster of stars near the galactic centre, as well as dusty objects called G-sources. It also incorporates data from the European Space Agency's Gaia DR3 mission.

Mimicking the Black Hole Shadow

Perhaps the most striking finding is that this dense dark matter core, when illuminated by surrounding material, casts a shadow strikingly similar to the famous image captured by the Event Horizon Telescope in twenty twenty-two. The dark matter core bends light so strongly that it creates a central darkness surrounded by a bright ring, closely matching what was assumed to be definitive evidence of a black hole.

How We Settle the Debate

The key to distinguishing between the two scenarios lies in photon rings. These are predicted to exist around true black holes but would be absent around a dark matter core. The GRAVITY interferometer at the Very Large Telescope in Chile could provide the precise measurements needed. Scientists from Argentina, Italy, Colombia, and Germany contributed to the research.