The universe’s intergalactic medium (IGM), composed primarily of ionized hydrogen and helium, contains a significant 5% of the universe’s normal matter, playing a crucial role in galactic evolution. Understanding this often-overlooked component of the cosmos is the focus of new research led by Sebastián López, an astronomer at the Facultad de Ciencias Físicas y Matemáticas (FCFM) at the University of Chile.
López’s work, conducted from Chile, analyzes the evolution of galaxies through the lens of the IGM – a persistent mystery in cosmology. He highlighted the increasingly important role Chile plays in astronomical research. “Chile has become what we call ‘the capital of astronomy,’ thanks to the most powerful telescopes in the world being located on our territory,” he stated to Café Plus.
This access to cutting-edge telescopes provides Chilean astronomers with privileged observing time, fostering a growing scientific community. “Chile, as a small country on the world stage, is becoming a relevant actor and is doing first-rate science, with astronomers born and educated in the country,” López added. The research is a collaborative effort involving professionals from the Universidad Católica de Valparaíso, the Pontificia Universidad Católica de Santiago, the European Southern Observatory (ESO), and the University of Chile.
The team employs a technique called spectroscopy to study the intergalactic material, analyzing how light from distant sources is affected as it travels millions of light-years to Earth. “We have formed a group dedicated to studying intergalactic material, using a technique called spectroscopy, with information that travels through the light beam, that is, from millions of years-light distance from Earth,” López explained. This approach allows researchers to probe the composition and structure of the IGM, offering insights into galaxy formation and evolution.
Galactic Groupings
López also discussed the common phenomenon of galactic collisions, which are large-scale gravitational interactions where galaxies merge over millions of years. While direct star-to-star collisions are rare due to the vast distances involved, the compression of gas and dust triggers new star formation. “I would say that half of the galaxies in the universe do not live in isolation, but rather in groups,” López noted. This finding underscores the interconnectedness of galactic structures and the importance of studying them collectively.
These processes unfold over immense timescales, spanning billions of years. “Unfortunately, the scales are gigantic, compared to a human life. But we can compile several galaxies or groups of these, at different times, and draw conclusions because light takes time to reach Earth,” López commented. Cosmological studies focus on the history of the universe, its formation, and evolution, while López’s work centers on the lifecycle of individual galaxies.
“We are more focused on this second aspect, as curious things happen in the life of galaxies that prevent star formation. And for that, it is important to analyze the intergalactic gas,” he emphasized. The research aims to understand the mechanisms that regulate star formation within galaxies, a key factor in their overall evolution.
López further explained that atoms make up only a small fraction (5%) of the universe, with dark matter comprising the remaining 95%. “atoms do help us trace and draw conclusions, while there is an important fraction of them that does not radiate, because the gas is very diffuse. For that, we employ a relatively new technique (redshift), to see the role of atoms in how galaxies evolve,” he concluded. The use of redshift allows scientists to study the faint signals from the IGM, providing valuable data on its properties and its influence on galactic evolution.
