The prevailing theory posits that at the very heart of our Galaxy resides a supermassive black hole: Sagittarius A* (Sgr A*). Its mass is roughly four million times that of the Sun, and stars belonging to the so-called S-cluster orbit around it. Nevertheless, some observations suggest inconsistencies with this standard model. Astrophysicists propose a bold alternative: instead of a terrifying singularity at the Milky Way’s center, there exists a gigantic sphere composed of dark matter.
The Anomaly of Cloud G2
In 2011, astronomers detected a gas cloud of three Earth masses hurtling directly toward the Galactic center. This object was dubbed G2. It presented an ideal opportunity to witness black hole “feeding” in real-time.
Expectation: Cosmic Spaghetti
Scientists predicted a catastrophe. The black hole’s gravity should have stretched the cloud into a thin thread—a process termed spaghettification. A portion of the gas ought to have fallen into the hole, heated up, and triggered a powerful burst of X-ray and radio emissions.
Reality: A Quiet Passage
In 2014, G2 reached its closest approach—the pericenter. And nothing happened. The cloud did not tear apart; it maintained its compactness and continued its flight. The black hole remained silent: no flare activity was registered.
This event was dubbed a “cosmic fiasco” for the standard model. However, in 2021, astronomers obtained evidence suggesting that cloud G2 represented a triple star system undergoing a merger. But there is also a more fundamental explanation.
The Ruffini-Argüelles Hypothesis
A team of scientists introduced the RAR model (Ruffini-Argüelles-Rueda). According to this, the Galaxy’s center is occupied by a dense core of dark matter particles, which they termed “darkinos.”
Darkinos are neutral, half-integer spin particles, classifying them as fermions. They adhere to the Pauli exclusion principle: two identical particles cannot occupy the same state. This generates a powerful quantum pressure that prevents the core from collapsing into a point, even under the influence of monstrous gravity.
Such an object is structured more complexly than a black hole. It possesses three regions:
The ultradense central part, known as the quantum core.
An intermediate layer—the atmosphere—where density gradually decreases.
A sparse outer shell—the halo—extending for thousands of light-years.
One-Way Ticket: What You Would See and Feel Falling into a Black Hole
How does this account for the survival of G2?
Unlike a black hole, the darkino core lacks an event horizon—the boundary from which not even light can return. It possesses a “soft” surface and an atmosphere. When cloud G2 approached the center, it encountered not the zone of fatal tidal forces from a singularity, but the dense atmosphere of dark matter particles.
The tidal forces were weaker, meaning the cloud did not fragment. Furthermore, G2 slowed down more than anticipated after its flyby. In the new model, this is explained simply by the friction of the cloud against the dense darkino particle medium.
Mathematical calculations confirm this: the dark matter model statistically describes G2’s motion far more accurately than the black hole model.
Stars of the S-Cluster
The primary argument for black hole proponents is the movement of the star S2. It accelerates to several percent of the speed of light, completing one orbit around the galactic center every 16 years.
However, 2020 calculations revealed a remarkable finding. If the mass of the darkino particles is tuned correctly (around 56 keV), S2’s orbit in the dark matter model barely differs from its orbit around a black hole. The difference is less than one percent.
Thus, star S2 only proves the existence of a compact mass at the center, but it does not precisely define its nature. It could be either a singularity or a dense ball of fermions.
Photo of the Galactic Center: Where is the Catch?
In 2022, the Event Horizon Telescope (EHT) captured an image of Sagittarius A*—a dark patch within a ring of light. Everyone assumed this was the shadow of a black hole.
But physics allows for alternatives. An ultra-dense darkino core is also capable of bending light. It creates an effect of gravitational lensing, forming a “brightness depression” at the center that outwardly closely resembles a black hole’s shadow. The calculated size of this shadow perfectly matches what the EHT photographed.
How to distinguish them? A black hole must have a photon ring—a thin, sharp line of light right at the edge of the shadow. A dark matter core lacks such a sharp boundary because it has no event horizon. Next-generation telescopes (ngEHT) will be able to perceive this difference.
A Unified Theory
The standard astrophysical model faces two issues in describing the galactic center:
The mismatch between the theoretical and actual behavior of stars near the galactic center.
The dark matter halo surrounding the galaxy, which is necessary to explain the rotation of stars at the outskirts.
The RAR model unifies these into one elegant system. The dense core in the center smoothly transitions into the sparse halo at the periphery. It is the same matter, just in different phase states.
Moreover, this model resolves a puzzle from the early Universe. Astronomers observe giant black holes where the Universe was only a few hundred million years old. By classical laws, they simply could not have grown that fast. In the new theory, it’s straightforward: if the mass of the dark matter core exceeds a critical threshold, it instantaneously collapses into a supermassive black hole.
According to this model, Sagittarius A* is an “unfulfilled” black hole. It simply hasn’t yet accumulated enough mass to collapse, so it remains a stable dark matter sphere.
Conclusion
Astronomy stands on the verge of a paradigm shift. The anomalous resilience of cloud G2 and data from the Gaia mission hint that the Milky Way’s center harbors not the dead end of a singularity, but a living, pulsating core of dark matter.
The next decade will be decisive. New instruments, such as the GRAVITY+ interferometer and ngEHT telescopes, will either find the photon ring and confirm the classical theory or definitively prove that the Universe is far stranger than previously believed.
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