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Astronomers have detected the oldest known examples of complex organic molecules in the universe, a new study reports. These carbon-based molecules , called polycyclic aromatic hydrocarbons, were found in an early galaxy that formed when the universe was only 10% of its current age.
Lead author Justin Spilker, an astronomer from Texas A&M University, explained that these molecules are not simple substances like water or carbon dioxide. Instead, they are large, Floppy Molecules containing dozens or even hundreds of atoms. On Earth, we encounter them in oil, coal reserves, and smog.
Probing the Early Universe’s Chemistry
Complex organic molecules are abundant in space, often associated with small dust grains. Astronomers study them to gain insights into activities within galaxies, such as the cooling rate of interstellar gas. However, detecting these molecules in distant galaxies that formed during the early stages of the universe has been challenging due to limitations in observatories’ sensitivity and the range of light wavelengths they can detect.
Through NASA’s powerful James Webb Space Telescope (JWST), Spilker and his colleagues successfully detected these molecules in a galaxy named SPT0418-47, located over 12 billion light-years away from Earth. This remarkable finding was made possible by leveraging gravitational lensing, a phenomenon where mass warps the fabric of space-time, acting like a magnifying glass for distant objects.
Unraveling the Mysteries of Early Galaxies
The light observed from SPT0418-47 began its journey less than 1.5 billion years after the Big Bang, pushing back the record for such detections by approximately a billion years. Spilker expressed amazement at how quickly the universe formed these large and complex organic molecules following the cosmic event.
Previous discoveries of the oldest complex organic molecules relied on extensive data from NASA’s Spitzer Space Telescope, requiring over a day’s worth of observations. In contrast, the JWST enabled the researchers to make the discovery in just one hour. Spilker highlighted that the JWST’s resolution allows for detailed analysis of the molecules’ distribution within the galaxy, providing insights beyond mere presence or absence.
Moreover, the presence of these molecules in SPT0418-47 is not evenly spread throughout the galaxy, with unknown reasons. This challenges the previous belief that these complex substances are exclusively associated with star formation. The researchers found regions with these molecules but no signs of star formation, as well as areas with active star formation but without the presence of these molecules.
Implications and Future Discoveries
Spilker emphasized the implications of these findings, suggesting that galaxies can rapidly form and produce complex molecules through rich chemistry in space. The study raises questions about the early formation of large molecules in galaxies and the factors influencing their presence or absence.
While the recent discoveries were made possible through the JWST’s mid-infrared instrument (MIRI), Spilker cautioned that the instrument’s performance is currently declining. NASA’s engineers are working to address the issue, but if the situation persists, future research of this nature may become unfeasible after the coming year.
In summary, the discovery of complex organic molecules in the early universe is a remarkable achievement. It provides valuable insights into the chemistry of early galaxies and challenges previous assumptions about the association of these molecules with star formation. Astronomers eagerly anticipate future advancements that will enable them to explore even more distant galaxies and unravel the mysteries surrounding the formation of large molecules in the cosmos.
