RIVERSIDE, Calif. -- Using data from NASA's James Webb Space Telescope ( JWST ), astronomers led by researchers at the University of California, Riverside have produced the most detailed map of the cosmic web ever made, tracing the network of galaxies all the way back to when the universe was one billion years old.
The cosmic web is the universe's vast, skeleton-like framework — a network of interwoven filaments and sheets of dark matter and gas that surround immense, nearly empty voids. It forms the underlying architecture of the cosmos, linking galaxies and clusters into a single, intricate, and far-reaching structure.
The study , which appears in The Astrophysical Journal, used the largest JWST survey conducted so far — the COSMOS-Web — to trace how galaxies form a network across 13.7 billion years of cosmic history.
Since its launch in 2021, JWST has transformed astronomy with its extraordinary sensitivity and sharpness. Its infrared instruments pick up faint, distant galaxies that were invisible to earlier observatories, allowing scientists to see further back in time than ever before, and through cosmic dust.
To harness this power, an international team designed COSMOS-Web, the largest General Observer (GO) program selected for JWST. The GO program is the primary way astronomers gain access to the telescope for their research. Covering a contiguous area of the sky about the size of three full Moons, the survey was designed to map the cosmic web.
"JWST has completely changed our view of the universe, and COSMOS-Web was designed from the start to give us the wide, deep view we need to see the cosmic web," said Hossein Hatamnia , a graduate student at UCR and Carnegie Observatories , and lead author of the study. "For the first time we can study the evolution of galaxies in cluster and filamentary structures across cosmic time, all the way from when the universe was a billion years old up to the nearby universe."
The nearby universe refers to our cosmic neighborhood within approximately 1 billion light-years. Approximately 5.88 trillion miles, a light-year is the distance light travels in one Earth year, used to measure massive distances in space.
Bahram Mobasher , a distinguished professor of physics and astronomy at UCR and Hatamnia's advisor, explained that the large-scale structure identified from the JWST cosmic web data is much more informative than earlier maps of the same region of sky taken by the Hubble Space Telescope. A direct side-by-side comparison, he said, shows how much the previous generation of data had been smoothing over structures.
"The jump in depth and resolution is truly significant, and we can now see the cosmic web at a time when the universe was only a few hundred million years old, an era that was essentially out of reach before JWST," Mobasher said. "What used to look like a single structure now resolves into many, and details that were smoothed away before, are now clearly visible."
Hatamnia explained that the improvement comes from two JWST strengths working together.
"The telescope detects many more faint galaxies in the same patch of sky, and the distances to those galaxies are measured far more precisely," he said. "Each galaxy can therefore be placed into the correct slice of cosmic time, sharpening the map's resolution."
In keeping with COSMOS's long tradition of open science, the team is releasing the large-scale structure maps publicly.
"The pipeline used to build the map, the catalog of 164,000 galaxies and their cosmic density, and a video showing the cosmic web evolving across billions of years, has been released to the public ," Mobasher said.
Mobasher and Hatamnia were joined in the study by scientists in the U.S., Denmark, Chile, France, Finland, Switzerland, Japan, China, Germany, and Italy.
The study was supported by grants from the European Union's Horizon 2020 research and innovation program.
The title of the paper is "Large-Scale Structure in COSMOS-Web: Tracing Galaxy Evolution in the Cosmic Web up to z ∼ 7 with the Largest JWST Survey."
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is more than 26,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual impact of more than $2.7 billion on the U.S. economy. To learn more, visit www.ucr.edu .
