Complex organic molecules have been observed by the James Webb Space Telescope in a galaxy that came into existence a mere 1.5 billion years following the formation of the universe.
In a groundbreaking discovery, the James Webb Space Telescope has detected the presence of polycyclic aromatic hydrocarbons (PAHs) in an ancient galaxy known as SPT0418-47. These complex organic molecules have long been associated with pollutants such as coal, oil, and smog, which pose significant risks to public health and ecosystems here on Earth. However, in the realm of astronomy, PAHs serve as celestial smoke signals, indicating regions where stars are undergoing rapid formation. This finding challenges the conventional understanding of PAHs as reliable tracers of star formation.
Led by astronomer Justin Spilker from Texas A&M University, the research team utilized the James Webb Space Telescope, the most advanced observatory ever launched, to explore the galaxy SPT0418-47. Their study, published in Nature, revealed a perplexing pattern: PAHs were found to be abundant in areas with low star formation activity, while they were scarce in regions where stars were being born at a high rate. This unexpected observation has left scientists with an intriguing mystery to unravel.
Spilker compares the situation to the familiar adage, "where there's smoke, there's fire." PAHs, which are prevalent in smoke, soot, and smog on Earth, were expected to be closely linked to areas of active star formation. However, the team found instances where PAHs were present without significant star formation, and vice versa. The discrepancy raises questions about the processes responsible for the distribution of these organic molecules and their connection to star formation.
One possibility suggested by Spilker is that the PAHs are being destroyed, potentially by shockwaves generated from supernova explosions. Alternatively, it is possible that the light emitted by newborn stars is not as closely associated with the presence of PAHs as previously believed. However, the exact cause of the observed differences remains elusive, indicating the need for further investigation.
The observations of SPT0418-47 were part of the TEMPLATES program, which aims to enhance our understanding of star formation in galaxies that existed within the first few billion years of the universe. The program focuses on a group of galaxies that are magnified by gravitational lensing, a phenomenon that occurs when the gravitational field of an object located closer to Earth amplifies the light from a more distant object, creating a bright, multi-part image known as an Einstein ring.
Spilker expresses his fascination with SPT0418-47, describing it as a long-standing favorite. The galaxy's selection for the initial observations with the James Webb Space Telescope was a deliberate choice due to its anticipated visual splendor. The team hopes to build on their findings by capturing more images using the unrivaled capabilities of the observatory, which may ultimately shed light on the peculiar variations in PAH distribution observed in their research.
The implications of the study extend beyond the specific galaxy under investigation. The results suggest that the evolution of organic molecules in early galaxies is far more complex than previously assumed. The well-established correlation between PAHs and star formation observed in younger galaxies seems to break down in SPT0418-47, indicating the presence of some mechanism responsible for the spatial variations of these molecules. Potential factors include the explosive deaths of stars within the galaxy or the distribution of dust grains throughout it. However, a clear explanation has yet to be uncovered.
Nevertheless, one undeniable outcome of this discovery is that it provides us with a glimpse into the universe's early stages, confirming that even at a mere 1.5 billion years old (just 10% of its current age), SPT0418-47 has undergone significant star formation, enriching its surroundings with heavy elements like carbon and oxygen. The detected PAHs, with their large and complex structures containing thousands of atoms,
