One of the earliest known black holes in the universe, ULAS J1120+0641, has surprised astronomers by growing larger than its host galaxy. New images from the James Webb Space Telescope (JWST) show this quasar, which existed about 12.9 billion years ago, surrounded by many early galaxies. Despite having neighbors, ULAS J1120+0641’s host galaxy lacks the mass needed to catch up. This raises intriguing questions about how such a large black hole could develop so quickly, leaving its galaxy behind.
Discovery Insights
The JWST spotted faint galaxies that earlier telescopes missed. These young galaxies glow from energized oxygen, hinting at star formation. However, even with 22 nearby sources, the future mass of these galaxies isn’t enough to balance the relationship between the black hole and its galaxy.
Meredith Stone from the University of Arizona emphasized that this imbalance is unusual. Typically, supermassive black holes grow in tandem with their galaxies, but ULAS J1120+0641 challenges this norm. The black hole likely raced ahead during the universe’s infancy, when conditions were vastly different.
Understanding Cosmic Growth
According to a Penn State University study, black holes have been slowing down over time. Fast-growing black holes emit high-energy X-rays as they consume material. Niel Brandt, an astronomy professor at Penn State, noted that the universe had more cold gas during its “cosmic noon,” the peak period of galaxy formation. This gas fueled both star formation and black hole growth.
As cosmic conditions evolved — due to events like supernova explosions — cold gas reservoirs diminished. This scarcity explains why mergers between rich galaxies might not enhance a mismatched system like ULAS J1120+0641.
The Growth Disparity
Stone’s team estimated that the host galaxy could theoretically reach about 60 billion suns through mergers with nearby galaxies. However, even then, the black hole would still constitute around 2.5% of the galaxy’s mass, which is significantly higher than typical ratios.
Recent research suggests that a companion galaxy is merging with ULAS J1120+0641, yet this may not substantially address the imbalance. The companion only contains a few billion suns, illustrating that one merger cannot rectify early growth discrepancies.
Unanswered Questions
The most intriguing possibility is that ULAS J1120+0641 could fall quiet in a smaller galaxy once its quasar phase ends. Without fresh gas, it wouldn’t sustain its brightness. If this scenario holds true, there might be more oversized black holes hidden in faint galaxies across the universe.
This discovery emphasizes the complexities of galaxy and black hole growth. Future research, especially focusing on hidden gas and other faint galaxies, will offer deeper insights. The study offers a fresh perspective on how some black holes may have thrived in the early universe while leaving their galaxies struggling to catch up.
For more in-depth information, you can read about these findings in The Astrophysical Journal here.
