Astronomers have used the James Webb Space Telescope to create the most detailed map yet of the cosmic web, the massive structure that connects all the galaxies in the universe. A research team led by the University of California, Riverside, traced this massive network back to its early state when the universe was only about 1 billion years old.
The cosmic network is the giant skeletal framework of the universe, composed of huge fiber-like structures and sheet-like structures made of dark matter and gas, which surround huge near-space regions called "voids." Together, these structures form the large-scale architecture of the universe, connecting galaxies and galaxy clusters over vast distances. The research results have been published in the Astrophysical Journal and are based on COSMOS-Web, the largest sky survey project in the history of the Webb telescope. Scientists used the survey data to study how galaxies formed and evolved in this interconnected network, spanning 13.7 billion years of cosmic history.
Since its launch in 2021, the Webb Telescope has revolutionized astronomical research with its exceptional sensitivity and image clarity. Its infrared instruments can detect faint, distant galaxies that were invisible to early telescopes, allowing scientists to reach back to earlier times in the universe and peer through cosmic dust clouds. To take full advantage of these capabilities, an international team developed the COSMOS-Web project, the largest universal observer program selected for the Webb telescope. The survey covers a continuous area of sky roughly the size of three full moons and is specifically designed to map the cosmic web.
"The Webb telescope revolutionized our understanding of the universe, and COSMOS-Web was designed from the beginning to provide the broad and deep views we need to observe the cosmic web," said first author Hossein Khatamniya, a graduate student at UC Riverside and the Carnegie Observatory. For the first time, it is possible to study the evolution of galaxies in galaxy clusters and fiber-like structures across cosmic time, from the birth of the universe 1 billion years ago to the nearby universe. "The so-called nearby universe refers to the area within about 1 billion light-years from the earth, and 1 light-year is approximately 5.88 trillion miles, which is used to measure the distance that light travels in a year."
Bahram Mobaser, distinguished professor of physics and astronomy at the University of California, Riverside and Khatamniya's mentor, said the new Webb data provide a more detailed view of large-scale cosmic structure than previous Hubble Space Telescope observations. Comparing the two data sets reveals that many structures that were once blurred together can now be clearly separated and studied in finer detail. "The improvements in depth and resolution are really significant," said Maubasel. "We are now able to see the cosmic network when the universe was only a few hundred million years old, an era that was largely inaccessible before the Webb telescope. What used to look like a single structure is now resolved into many structures, and details that were previously smoothed are now clearly visible."
Khatamniya explained that this improvement results from the combination of two key advantages of the Webb telescope. "This telescope detects many more faint galaxies in the same area of the sky, and the distances to these galaxies are measured much more precisely," he said. "So each galaxy can be placed into the correct slice of cosmic time, thereby increasing the resolution of the map."
Continuing the COSMOS project's tradition of open science, the research team is publicly releasing large-scale structural maps. "The data processing pipeline used to construct the map, a star catalog of 164,000 galaxies and their cosmic densities, and videos showing the evolution of the cosmic network across billions of years are all available to the public," said Maubasel. The research also involved scientists from the United States, Denmark, Chile, France, Finland, Switzerland, Japan, China, Germany and Italy, and was supported by funding from the European Union's Horizon 2020 research and innovation program.