An international research team, including Andrea Pallottini of the Department of Physics at the University of Pisa, has discovered an enormous reservoir of cold molecular gas in REBELS-25, a galaxy that existed when the Universe was only 700 million years old — less than 5 per cent of its current age.
This gas represents the fuel needed for the formation of new stars, and its discovery helps explain how the first galaxies were able to grow so rapidly during the earliest stages of cosmic history. The study was published in the journal Monthly Notices of the Royal Astronomical Society.
“For the first time, we have direct evidence that some galaxies in the early Universe were extremely rich in molecular gas, the fuel from which stars are born,” comments Andrea Pallottini of the Department of Physics at the University of Pisa. “Understanding the physical properties of this material is essential for reconstructing the processes that led to the formation of the first galaxies and understanding the evolution of the Universe during its first few billion years.”
The discovery was made possible by observations carried out with the Very Large Array (VLA) radio telescope in the United States and the ALMA interferometer in Chile. The researchers identified the signal emitted by carbon monoxide within the galaxy, a crucial tracer used to measure the amount of molecular gas available.
The findings also open new possibilities for the study of the young Universe. Future next-generation radio telescopes will make it possible to extend these observations to a much larger number of galaxies, providing an increasingly detailed view of the earliest phases of cosmic evolution.
The study was led by Karin Cescon, a PhD candidate at Leiden University (the Netherlands), and involved researchers from numerous institutions, including Leiden Observatory, the National Radio Astronomy Observatory (NRAO) in the United States, the European Southern Observatory (ESO), the Cosmic Dawn Center in Denmark, and several universities and research centres across Europe, Asia and North America.
