Dark Matter Core Proposed as Alternative to Black Hole at Milky Way's Center

Recent research challenges the longstanding belief that a supermassive black hole, known as Sagittarius A* (Sgr A*), resides at the center of the Milky Way. Instead, scientists propose that a dense core of fermionic dark matter could account for the gravitational forces observed in this region.

Traditionally, Sgr A* has been identified as the massive object influencing the rapid orbits of stars near the galactic center. However, the new study suggests that a specific form of dark matter, composed of lightweight subatomic particles called fermions, might form a compact core surrounded by a diffuse halo. This structure could mimic the gravitational effects attributed to a black hole.

The model posits that the dense dark matter core would exert a gravitational pull similar to that of a black hole, explaining the high velocities of stars close to the center. Additionally, the surrounding dark matter halo could account for the smoother rotation curves observed in the galaxy's outer regions.

Supporting this hypothesis, data from the European Space Agency's GAIA DR3 mission revealed a decline in orbital speeds at great distances from the galactic center, a pattern known as the Keplerian decline. This observation aligns with predictions from the dark matter halo model when combined with the known mass of the Milky Way's disk and central bulge.

An international team of scientists conducted this research, including members from the Institute of Astrophysics La Plata in Argentina, the International Centre for Relativistic Astrophysics Network, and the National Institute for Astrophysics in Italy. Dr. Carlos Argüelles of the Institute of Astrophysics La Plata stated, "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."

Further bolstering the dark matter core theory, previous studies demonstrated that such a core could produce a shadow-like feature when illuminated by an accretion disk. This feature closely resembles the image captured by the Event Horizon Telescope for Sgr A*. Lead author Valentina Crespi noted, "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."

While current data cannot definitively favor the dark matter core model over the traditional black hole explanation, future observations may provide clarity. Instruments like the GRAVITY interferometer on the Very Large Telescope in Chile, along with searches for photon rings, could offer decisive evidence. If confirmed, this dark matter core model could significantly alter our understanding of the massive object at the heart of the Milky Way.