For the first time, astronomers have captured direct images of the cosmic web, the universe’s largest known structure, which is a network of filaments connecting galaxies across vast distances.
This groundbreaking discovery opens new avenues for understanding galaxy formation, evolution, and the elusive dark matter that constitutes about 80% of the universe’s mass.
A Milestone in Cosmic Exploration
The cosmic web was first imaged in 2014 using radiation from a distant quasar, and later in 2019, young star-forming galaxies helped illuminate it. However, the latest images are the first to directly capture the cosmic web’s light, revealing filaments between 10 billion and 12 billion light-years away. Christopher Martin, a professor of physics at the California Institute of Technology and the lead author of the study, stated that this discovery allows us to see the filamentary structures “without a lamp,” unlike before.
The Role of the Keck Cosmic Web Imager
The images were captured using the Keck Cosmic Web Imager, located at the Keck Observatory atop the Mauna Kea volcano in Hawaii. The instrument was specifically tuned to detect emissions from hydrogen gas, the main component of the cosmic web. The two-dimensional images were later stacked to form a three-dimensional map, providing a comprehensive view of the cosmic web. “We are basically creating a 3D map of the cosmic web,” said Martin.
Implications for Understanding the Universe
According to cosmological simulations, over 60% of the hydrogen created by the Big Bang collapsed to form a sheet, which then broke apart to create the cosmic web. These filaments not only connect galaxies but also feed them gas for growth and star formation. The direct images of these crisscrossing filaments can help scientists better understand how galaxies form and evolve over time.
In summary, the first direct images of the cosmic web mark a significant advancement in our understanding of the universe’s structure and composition. This research, described in a paper published in the journal Nature, offers a whole new way to study the universe, according to Martin.