Astronomers have discovered a massive hidden fuel source in a young galaxy cluster, revealing new clues about how galaxies form and grow.
Using the powerful Atacama Large Millimeter/submillimeter Array (ALMA) and additional data from the Atacama Pathfinder Experiment (APEX), researchers found a vast amount of molecular gas in a protocluster of galaxies called SPT2349-56.
This cluster, located about 12 billion light-years away, is one of the earliest galaxy clusters in the universe.
Galaxy clusters are the biggest structures in space, and scientists are eager to understand how they form. Protoclusters like SPT2349-56 offer a rare opportunity to see galaxies coming together in the early universe.
The research, led by Dazhi Zhou from the University of British Columbia and published in The Astrophysical Journal Letters, focused on molecular gas—the key ingredient for star formation.
Hydrogen gas fuels the birth of stars and plays a crucial role in galaxy evolution.
Key findings
- Missing Gas: When comparing high-resolution ALMA data with lower-resolution observations from ALMA’s Atacama Compact Array (ACA) and APEX, scientists found 75% more carbon monoxide (CO) than what was visible in the sharper images. This means a huge amount of gas was previously hidden.
- A Giant Gas Cloud: This extra gas isn’t just in small, unseen galaxies. Instead, it forms a massive, spread-out reservoir surrounding the cluster.
- Fuel for Star Formation: This hidden gas could explain the extreme star-making activity in SPT2349-56. The presence of so much gas means that stars will continue forming for more than 400 million years.
- Early Signs of a Galaxy Cluster’s Atmosphere: Scientists believe this extended gas cloud might be the early version of the intracluster medium (ICM), a hot and diffuse gas that fills mature galaxy clusters.
“This discovery shows the power of ALMA,” said Zhou. “By using different configurations, we could see both individual galaxies and the bigger picture—the hidden gas fueling their star formation.”
SPT2349-56 is an extreme system, forming stars at a rate 10,000 times faster than the Milky Way but within a similar-sized region.
This challenges existing models of galaxy formation, as no previous simulations predicted such an enormous gas concentration.
These findings suggest that high-resolution telescopes, while excellent for studying single galaxies, may miss important gas reservoirs in early galaxy clusters.
Future ALMA studies will be crucial to fully understanding this hidden fuel source and how it shapes galaxy evolution.
Source: National Radio Astronomy Observatory.
