LAS CRUCES — In a study published in the June issue of the Astrophysical Journal, a team of New Mexico State University astronomers introduced a new way to think about supermassive black holes. Rather than acting as cosmic vacuum cleaners, the researchers argue that the outer regions of the accretion disks surrounding these black holes function more like a nursery, allowing dust to clump together and form objects that can reach masses comparable to the Sun.
From dust to planetary‑mass objects
“We’re finding objects that are a thousand times the mass of the Earth, but built of pure dust,” said associate professor Wladimir Lyra, who heads the project. Using computer simulations, Lyra’s group modeled the conditions in the outer parts of an active galactic nucleus (AGN) disk and observed how dust particles coalesce over millions of years. The resulting bodies, sometimes called “AGN embryos,” can grow to several hundred Earth masses and, in some cases, approach the mass of a star.
“AGN Channel” offers a bottom‑up formation path
The researchers label the mechanism the “AGN Channel.” In this scenario, low‑mass black holes orbiting within the AGN disk behave like planetary embryos, migrating, colliding, and merging much as protoplanets do around a young star. The process is the opposite of the traditional top‑down model of star formation, which relies on the gravitational collapse of a massive gas cloud.
“You first form the building blocks and then accrete gas and then boom, you form a star,” Lyra explained. The team’s simulations suggest that the same environment could also produce intermediate‑mass black holes that later merge, creating black holes a few hundred times the Sun’s mass.
Observational prospects
To test the theory, the scientists point to microlensing – a technique first proposed by Albert Einstein – as a way to spot the dusty embryos when they pass in front of the bright AGN core. The upcoming Nancy Grace Roman Space Telescope, slated for launch in August, will have a field of view far larger than the Hubble Space Telescope and could capture the subtle brightening patterns predicted by the model.
“Once planets orbiting in the AGN disk pass the line of sight of the AGN, they will act as a gravitational lens for the bright AGN,” Lyra said. Detecting such events would provide direct evidence for the AGN Channel.
Future work and gravitational‑wave links
The team also plans to extend their simulations to predict electromagnetic signatures that could accompany the gravitational‑wave bursts expected when two massive black holes merge. Those waves, detectable by the Laser Interferometer Space Antenna (LISA) scheduled for launch in the mid‑2030s, would offer another avenue to confirm the theory.
Graduate researcher Bhupendra Mishra, now teaching at Santa Fe Preparatory School, highlighted the broader implications: “These black holes are ginormous – hundreds or thousands of times the size of the Sun – and if they move toward the center they could produce a signal detectable by LISA.”
Local impact
The study underscores the growing role of New Mexico’s research institutions in frontier astrophysics. NMSU’s involvement brings high‑profile science to the Las Cruces community and offers students hands‑on experience with cutting‑edge computational modeling.
For more information, contact Minerva Baumann at [email protected] or call 575‑646‑7566.
Original reporting: Organ Mountain News (Las Cruces / Doña Ana County) — read the source article.
