Astronomers have used a new technique to find a rich population of baby galaxies growing up in the early Universe. Their findings, made possible by the Atacama Large Millimeter/Submillimeter Array (ALMA), provide valuable insights into the evolution of galaxies in the distant past.
The team, led by researchers from the University of California, Berkeley, employed a novel approach that utilized ALMA data to detect carbon monoxide gas in galaxies that were forming 12 billion years ago, when the Universe was only about 10 percent of its current age. This approach significantly improves the sensitivity and efficiency in finding these distant, dusty galaxies, which are challenging to observe.
The discovered galaxies are called Lyman-alpha emitters (LAEs) and are characterized by intense ultraviolet radiation emitted from hydrogen gas surrounding young, massive stars. ALMA observations revealed carbon monoxide gas within these galaxies, a critical component for understanding their star formation processes.
The observations showed that the rate of star formation in these young galaxies is highly efficient compared to nearby, similar-sized galaxies observed in our current universe. This finding could result in a paradigm shift in our understanding of galaxy evolution and the assembly of galaxies in the early Universe.
Previous surveys focusing on optical or infrared wavelengths encountered significant limitations in exploring the vast population of LAEs. However, by targeting carbon monoxide gas that emits at millimeter wavelengths, ALMA provides astronomers with a more direct probe of the gas reservoir that fuels star formation.
Lead author Xiaohui Fan and co-author Richard Ellis of University College London highlighted the significance of their discovery, stating that it challenges existing theories because "you don't expect an infant to look so grown-up." The team's findings suggest that a more thorough investigation is necessary to understand how gas, stars, and galaxies formed and assembled so quickly in the early Universe.
Further observations with ALMA and the planned Next-Generation Very Large Array (ngVLA) offer exciting prospects for exploring the earliest galaxies and unlocking more secrets of the Universe's past.
