Scientists might finally have an answer to a cosmic puzzle that’s stumped them since the James Webb Space Telescope (JWST) began its work in 2022. When astronomers turned their lenses toward the early universe, they discovered supermassive black holes that formed when the universe was less than 1 billion years old. This phenomenon contradicted existing models of cosmic evolution.
A new study suggests that a “feeding frenzy” among smaller black holes might explain how these massive entities formed so quickly. Daxal Mehta, leading the research at Maynooth University, notes that early black holes grew rapidly in chaotic conditions, consuming nearby material during this frenzied period.
Using advanced computer simulations, researchers found that the rich gas environments in the early universe allowed black holes to exceed the “Eddington limit.” This limit typically restricts how fast a black hole can consume material before radiation forces away additional matter. When black holes exceed this limit, they experience “super-Eddington accretion,” bridging the gap between smaller star-mass black holes and the giant supermassive ones we observe today.
Historically, these supermassive black holes sit at the center of large galaxies, but finding them as early as 500 million years after the Big Bang raises questions. Theory suggests that growing into supermassive black holes takes at least 1 billion years through mergers and accretion.
As John Regan, a member of the research team, pointed out, it’s puzzling to see such large black holes so early. It’s akin to a family with towering teenagers and a toddler who’s just as tall. How did that happen? The same mystery applies to these early black holes, which seem to have grown unexpectedly fast.
The team concluded that supermassive black holes emerging so quickly might have started as “light seeds,” weighing ten to a few hundred times the sun, rather than “heavy seeds” at 100,000 times the sun. Their findings challenge previous beliefs that massive seeds were essential for rapid black hole growth. As Regan stated, common stellar mass black holes could grow at extraordinary rates under the right conditions.
This research underscores the importance of high-resolution simulations in exploring the early universe. As Regan states, the early cosmos was more turbulent and populated with massive black holes than expected. To collect evidence supporting this theory, future observations might depend on detecting gravitational waves—tiny ripples in space that mergers of these early black holes would produce.
Significantly, the Laser Interferometer Space Antenna (LISA), a joint mission by the European Space Agency and NASA, is set to launch in 2035. This space-based gravitational wave detector could provide crucial insights into the mergers of these rapidly growing black holes.
This research was published in the journal Nature Astronomy and offers a fresh perspective on our understanding of black hole formation.
