Black holes are often imagined as cosmic vacuum cleaners that simply swallow everything nearby.
But new research suggests the environment around supermassive black holes may also be surprisingly creative, providing a nursery where enormous planets—and perhaps even new stars—can form.
Wladimir Lyra, an astronomer at New Mexico State University, and his colleagues used computer simulations to investigate the dusty disks surrounding actively feeding supermassive black holes.
Their study, published in The Astrophysical Journal, suggests these extreme environments could potentially produce millions of massive planets.
At the center of some galaxies lies an active galactic nucleus, or AGN. It forms when gas and other material fall toward a supermassive black hole, creating a hot, bright disk around it.
While conditions close to the black hole are extremely violent, the researchers found that the cooler outer regions of the disk may resemble the planet-forming disks surrounding young stars.
In these outer regions, tiny dust particles can gradually gather together. The team’s simulations showed that this dust could form objects thousands of times more massive than Earth. Some may even approach the mass of the sun.
The researchers describe these objects as planets made initially from dust. As they grow, they can attract large amounts of surrounding gas, potentially becoming enormous gas giants far more massive than Jupiter.
Some could become so massive that nuclear fusion eventually begins inside them, transforming them into stars. That would represent an unusual route to star formation.
Normally, stars form when huge clouds of gas become unstable and collapse under their own gravity. Lyra’s proposed mechanism works in the opposite direction. Small pieces of material first join together, creating increasingly massive objects that then collect gas until they become stars.
These massive stars could later collapse and form black holes. Over time, those black holes might migrate through the disk and merge with others, producing black holes hundreds or even thousands of times the sun’s mass.
Such mergers could create gravitational waves—ripples in spacetime that future observatories such as the European Space Agency’s LISA mission may be able to detect.
But how can astronomers test whether these strange planets really exist?
One possibility is gravitational microlensing. When a massive object passes between an observer and a distant source of light, its gravity bends and magnifies the background light. Planets orbiting within an AGN disk could therefore produce distinctive temporary changes in the brightness of the AGN.
The researchers hope that NASA’s Nancy Grace Roman Space Telescope, designed to conduct wide-field infrared observations and discover planets using microlensing, could help search for these signatures.
Meanwhile, the team is developing more sophisticated simulations that include spiraling gas, magnetic fields and turbulence around black holes.
If the theory is confirmed, supermassive black holes may need an image makeover. Their surroundings may not simply be places where matter disappears—they could also be extraordinary cosmic factories capable of building giant planets, stars and eventually new black holes.
Source: KSR.
