JWST maps cosmic web in record detail back to universe’s first billion years

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.

What the cosmic web reveals

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.

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.”

How COSMOS-Web powers the map

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 clusters 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.

Sharper views than Hubble allowed

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.”

Sharing the cosmic web with everyone

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, have 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.

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Sadie Harley

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Robert Egan

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