Active supermassive black holes may help form massive planets

Astronomers have uncovered a surprising new pathway for the formation of massive planets, and potentially even stars, near the hearts of galaxies, where supermassive black holes reside. According to a study led by Wladimir Lyra, an associate professor of astronomy at New Mexico State University, the intense environments surrounding these colossal black holes might serve as nurseries for celestial bodies far larger than previously imagined. Lyra’s research suggests that the outer regions of accretion disks around supermassive black holes contain conditions similar to those found in protoplanetary disks around young stars. In these areas, dust particles can coalesce into massive objects, some reaching sizes comparable to the Sun. This discovery challenges conventional wisdom about how such large structures form, offering a novel explanation rooted in the dynamics of material swirling around black holes. The findings stem from a collaborative effort initiated in 2010 involving Lyra and researchers at the American Museum of Natural History, including Barry McKernan, Saavik Ford, and Mordecai-Mark Mac Low. Bhupendra Mishra, who later joined the team while working at Santa Fe Preparatory School, contributed significantly to the research. Their work culminated in a paper titled “Active Galactic Nucleus Tori: Potential Birthplace to Millions of Planets,” published in The Astrophysical Journal. According to Lyra, the process involves smaller black holes orbiting within the disks of supermassive black holes behaving similarly to planetary embryos around the Sun. These objects migrate, alter their orbits, and collide, leading to the formation of increasingly massive entities. This mechanism, dubbed the “AGN Channel,” represents a distinct method of creating heavy black holes, one that differs fundamentally from existing theories. Computer models developed by the team simulated the behavior of dust in the outer regions of these disks. They demonstrated how dust particles aggregate over millions of years, gradually forming substantial planetary masses. The results were unexpected in both scale and quantity, revealing that the number and size of potential planets formed near active galactic nuclei could be staggering. Mishra highlighted the significance of the discovery, noting that some of the newly identified exoplanets could reach masses sufficient to initiate nuclear fusion, effectively transforming them into stars. This marks the first observed mechanism for star formation through a bottom-up approach, contrasting sharply with the traditional top-down gravitational collapse model. The implications extend beyond planetary formation. Lyra’s team posits that the massive stars generated in these environments could eventually collapse into black holes themselves. These newly formed black holes, ranging from hundreds to thousands of times the mass of the Sun, might later merge, contributing to the creation of heavier black holes. Such mergers could generate detectable gravitational waves, which future instruments like the Laser Interferometer Space Antenna (LISA) might observe. Scheduled for launch in the mid-2030s by the European Space Agency, LISA will consist of three spacecraft arranged in an equilateral triangle. Its mission is to detect gravitational waves from cosmic events, including the mergers of massive black holes. If the predictions hold true, signals from these mergers could provide crucial insights into the origins of the most massive black holes in the universe. The research opens new avenues for understanding the complex interplay between black holes, stars, and planets. By identifying an alternative route for star and planet formation, scientists gain a broader perspective on the processes shaping the cosmos. As further observations and data emerge, the role of supermassive black holes in nurturing celestial bodies may prove to be far more influential than previously recognized.