Astronomers have confirmed the existence of the earliest and most distant black hole, located in a galaxy known as CAPERS-LRD-z9. This black hole, which has been measured at approximately 300 million solar masses, emerged just 500 million years after the Big Bang. At that time, the Universe was only about 3 percent of its current age, making this discovery significant in understanding the early cosmos.
The findings, which have been published in the Astrophysical Journal Letters, offer new insights into a mysterious class of celestial objects called Little Red Dots (LRDs). These small, bright, red entities appeared around 600 million years post-Big Bang and faded away within less than a billion years. They have only recently been detected thanks to the advanced infrared capabilities of the James Webb Space Telescope (JWST), allowing astronomers to explore the Cosmic Dawn—the Universe’s earliest epochs.
This newly confirmed black hole is categorized as an active galactic nucleus (AGN), characterized by a bright, rapidly feeding black hole at a galaxy’s center. The red hue observed is attributed to a glowing cocoon of gas and dust surrounding the black hole, leading to its classification as a “black hole star.” The gravitational forces exerted by this supermassive black hole are astonishing, causing surrounding gas to whirl at speeds of approximately 3,000 kilometers (about 1,864 miles) per second, which is roughly 1 percent of the speed of light.
According to Anthony Taylor, an astrophysicist at the University of Texas at Austin, the extreme conditions around black holes create unique signatures detectable through spectroscopy. This technique involves splitting light into its constituent wavelengths to analyze the velocity of celestial objects. When light from gas near the black hole shifts to red, it indicates that the gas is moving away from the observer. Conversely, light moving toward an observer appears bluer, revealing valuable information about the object’s speed and behavior.
The confirmation of CAPERS-LRD-z9 supports the hypothesis that LRDs harbor supermassive black holes. These black holes may reach astonishing sizes, with some estimated at up to 10 million solar masses within their first billion years. In comparison, the supermassive black hole at the core of the Milky Way is approximately 4 million solar masses. Notably, the black holes at the center of LRDs might be classified as “overmassive,” with mass ratios nearing 10 percent to 100 percent of their host galaxies’ stellar masses.
The black hole at the heart of CAPERS-LRD-z9, weighing around 300 million solar masses, accounts for nearly half the total mass of all stars in its galaxy. In contrast, central black holes in nearby galaxies typically represent only about 0.1 percent of their stellar mass. The compact nature of CAPERS-LRD-z9 is such that even the JWST cannot resolve it; it stretches a mere 1,140 light-years across, placing it among the dwarf galaxies orbiting the Milky Way.
Researchers propose two pathways for a black hole to achieve such massive proportions within just 500 million years. The first involves a large “seed” black hole growing at the Eddington limit, possibly starting with a mass around 10,000 solar masses. Alternatively, it might begin from a smaller seed of about 100 solar masses, requiring a more aggressive growth rate, known as the super-Eddington rate, fueled by the dense gas enveloping it.
These primordial seeds may have originated from black holes formed in the aftermath of the Big Bang or from the collapse of Population III stars. They could also result from runaway collisions in dense star clusters or the direct collapse of massive primordial gas clouds.
Overall, this research highlights that LRDs were likely ephemeral phenomena in the early Universe, potentially serving as a foundational stage in galactic evolution that may have contributed to the formation of the Milky Way. Taylor concluded, “When looking for black holes, this is about as far back as you can practically go. We’re really pushing the boundaries of what current technology can detect.”
