Astronomers have discovered a supermassive black hole, RACS J0320-35, located approximately 12.8 billion light-years away, that is growing at a rate significantly exceeding theoretical limits. This discovery, made using NASA's Chandra X-ray Observatory, offers crucial insights into the universe's early development, approximately 920 million years after the Big Bang.
The black hole, estimated to be a billion times the mass of our Sun, is accreting matter at a rate 2.4 times higher than the Eddington limit. This limit typically dictates the maximum rate at which a black hole can grow before its own radiation pressure halts further accretion. The observation of RACS J0320-35 surpassing this limit so early in the universe's history has surprised scientists, with some describing the finding as "a bit shocking."
This significant discovery was the result of an international collaboration involving researchers from the Faculty of Sciences of the University of Lisbon and the Institute of Astrophysics and Space Sciences. They utilized data from multiple observatories, including the Australian Square Kilometer Array Pathfinder, the Dark Energy Survey, the Gemini-South Telescope, and the Chandra X-ray Observatory.
José Afonso, a professor at the Faculty of Sciences and researcher at the Institute of Astrophysics and Space Sciences, commented on the enigmatic nature of the early universe. He noted that the first billion years are proving to be increasingly mysterious, with the discovery of gigantic black holes that were previously thought to be impossible, possessing extreme properties at that early stage.
The implications of RACS J0320-35's rapid growth are substantial. Current models suggest that black holes growing at or below the Eddington limit would need immense initial masses to reach a billion solar masses within the first billion years. However, the super-Eddington growth rate of RACS J0320-35 indicates that black holes might have started with more modest masses and still achieved colossal sizes rapidly. This finding opens new avenues for understanding the formation of the earliest supermassive black holes.
Furthermore, RACS J0320-35 exhibits powerful jets of particles moving at near-light speeds, a phenomenon often associated with its extraordinary growth rate. Researchers are exploring the direct link between rapid accretion and jet formation, which could provide deeper insights into the complex dynamics of these early cosmic powerhouses.
The ongoing study of RACS J0320-35 is expected to refine our understanding of the universe's infancy. By providing evidence of black holes growing at previously unimaginable rates, this discovery compels a re-evaluation of existing astrophysical models and highlights the dynamic evolution of the cosmos.