At a Glance
- Astronomers used the James Webb Space Telescope to create the largest and deepest catalog of galaxy groups ever detected, covering a period from 12 billion to 1 billion years ago.
- The catalog includes nearly 1,700 galaxy groups and proto-clusters, offering new insights into how galaxies evolve through mergers, dark matter, and supermassive black holes.
- Galaxy groups, which are gravitationally bound collections of galaxies, help scientists understand the cosmic web and the evolution of structures like our Local Group.
- Comparing ancient and modern galaxy groups reveals that early galaxies were more irregular and star-forming, while present-day ones are more structured with spiral or elliptical shapes.
- This research advances our understanding of cosmic history and the influence of dark matter on galaxy formation and the universe’s large-scale structure.
Astronomers have made a groundbreaking discovery using data from the James Webb Space Telescope (JWST), cataloging the largest and deepest sample of galaxy groups ever detected. The catalog, which includes nearly 1,700 galaxy groups, spans a vast range of cosmic time, from 12 billion years ago to just 1 billion years ago. This discovery provides crucial insights into the evolution of galaxies and the universe’s large-scale structure. The findings were made possible by JWST’s high-resolution imaging capabilities, allowing astronomers to observe galaxies millions of light-years away, offering a glimpse into the early universe.
The new catalog, set to be published in Astronomy and Astrophysics, includes galaxy groups and proto-clusters, which are early stages of galaxy clusters. The research team, led by Ghassem Gozaliasl of Aalto University, aims to study how galaxies interact within these groups. These interactions, such as mergers and the influence of dark matter and supermassive black holes, play a significant role in the transformation of galaxies over time. Studying galaxy groups is key to understanding the formation of individual galaxies and the largest structures in the universe.
Galaxy groups are dense regions where galaxies are bound together by gravity. These groups, which can consist of just a few or several dozen galaxies, are important for understanding the cosmic web—the vast network of galaxies connected by filaments and walls. Our Milky Way galaxy, for example, is part of the Local Group, a small galaxy group that also includes the Andromeda galaxy. The research team studied these cosmic “families” to better understand how galaxies evolve through interactions and mergers within these environments.
The team can explore how galaxy structures change over cosmic history by comparing early galaxy groups with those closer to our time. One key observation is that galaxies in the early universe were more irregular and formed stars at a higher rate. In contrast, galaxies closer to the present day are more structured, with many having the familiar spiral or elliptical shapes. This research sheds light on how galaxies evolved and helps scientists address long-standing questions about the universe’s formation and the role of dark matter in shaping it.
References
- Toni, G., Gozaliasl, G., Maturi, M., Moscardini, L., Finoguenov, A., Castignani, G., Gentile, F., Virolainen, K., & et al. (2025). The COSMOS-Web deep galaxy group catalog up to z=3.7. Astronomy & Astrophysics. https://doi.org/10.1051/0004-6361/202553759
- Aalto University. (2025, April 29). Astronomers observe largest ever sample of galaxies up to more than 12 billion light years away. Phys.Org; Aalto University. https://phys.org/news/2025-04-astronomers-largest-sample-galaxies-billion.html
