🪐 Millions of planets could be born near supermassive black holes

Millions of planets could come into being in the most turbulent regions of galaxies, near supermassive black holes. For a long time, these areas were considered hostile to world formation, but a team of researchers has just demonstrated the opposite.

These zones, called active galactic nuclei (AGN), sometimes shine brighter than all the stars in their galaxy combined. The idea that planets could form there exceeds expectations.


Active galactic nuclei are powered by supermassive black holes that pull in immense quantities of gas and dust. This matter swirls in an accretion disk before being partially swallowed, while another part is ejected as plasma jets at speeds close to the speed of light. The intense friction within the disk makes it radiate across the entire electromagnetic spectrum, producing exceptional luminosity.

What surprises scientists most is that these accretion disks, though rich in gas and dust, are extremely turbulent. Usually, planetary formation is associated with calm protoplanetary disks around young stars. Yet, at the edges of these giant disks, temperatures and conditions could resemble those that gave birth to the planets of our Solar System. Gradually, dust could clump together and form worlds.

To test this hypothesis, the team developed a computer model of a supermassive black hole and its accretion disk. By adding data on conditions at the disk's boundaries, they simulated the evolution of dust over millions of years. The result astounded them: millions of planets with the mass of Jupiter, or even more massive, could form tens of parsecs (about 30 to 100 light-years) from the black hole. These dust giants would resemble lava spheres.


In a gas-rich disk, long dust filaments form and collapse into planets. Around a star, this process produces only a few worlds, but near a supermassive black hole, the available gas quantity is much larger, allowing the creation of millions of planets. Once formed, these planets gradually migrate outward, moving away from the black hole.

The researchers hope to detect these planets using gravitational lensing. This phenomenon, which distorts and amplifies the light from a distant object, could reveal the presence of planet clusters at the edges of an AGN disk. However, finding an active nucleus offering such a configuration requires a lot of luck. The team plans to refine its model to improve detection chances.

This discovery, if confirmed, would change our understanding of planetary formation in the Universe. The surroundings of supermassive black holes, far from being barren, could host myriads of unexpected worlds. The next steps will involve observing these regions with greater precision, perhaps using future generations of telescopes. In the meantime, astrophysicists have a new avenue to explore the origin of planets.