Astronomers using NASA’s James Webb Space Telescope (JWST) have created the most detailed map ever made of the cosmic web, the enormous structure that connects galaxies throughout the universe. Led by researchers at the University of California, Riverside, the team traced this vast network back to a time when the universe was only about one billion years old.
The cosmic web is the immense, skeleton-like framework of the universe. It consists of filaments and sheets made of dark matter and gas that surround gigantic, mostly empty regions of space known as voids. Together, these structures form the large-scale architecture of the cosmos, linking galaxies and galaxy clusters across enormous distances.
The findings were published in The Astrophysical Journal. Researchers relied on COSMOS-Web, the largest JWST survey carried out so far, to study how galaxies have been arranged within the cosmic web over 13.7 billion years of cosmic history.
JWST Opens a New View of the Universe
Since launching in 2021, JWST has dramatically expanded scientists’ ability to study the distant universe. Its highly sensitive infrared instruments can detect faint galaxies that earlier telescopes could not see, allowing astronomers to peer farther back in time and through thick clouds of cosmic dust.
To take advantage of those capabilities, an international team created COSMOS-Web, the largest General Observer (GO) program selected for the space telescope. The GO program is the main process researchers use to gain observing time with JWST. The survey covers a continuous section of sky roughly equal in size to three full Moons and was specifically 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 the region within about 1 billion light-years of Earth. A light-year, which equals approximately 5.88 trillion miles, measures the distance light travels in one year.
Cosmic Web Revealed in Greater Detail
Bahram Mobasher, a distinguished professor of physics and astronomy at UCR and Hatamnia’s advisor, said the new JWST-based map reveals much more information than earlier observations of the same area taken by the Hubble Space Telescope. According to Mobasher, direct comparisons show that previous data blurred together structures that JWST can now clearly separate.
“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 said the sharper map comes from two major strengths of JWST 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.”
Public Release of the Cosmic Web Data
Continuing COSMOS’s tradition of open science, the research team has made the large-scale structure maps publicly available.
“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.
The paper is titled “Large-Scale Structure in COSMOS-Web: Tracing Galaxy Evolution in the Cosmic Web up to z ∼ 7 with the Largest JWST Survey.”
Researchers from the U.S., Denmark, Chile, France, Finland, Switzerland, Japan, China, Germany, and Italy also contributed to the study.
Funding for the research came from grants provided through the European Union’s Horizon 2020 research and innovation program.