An international team of scientists has unveiled the most detailed map yet of dark matter, the invisible substance comprising roughly 85% of the universe’s mass [[1]]. Utilizing the advanced capabilities of the james Webb Space Telescope, the new map-covering an area three times the size of the full moon-promises to reshape our understanding of cosmic structures and galaxy formation. published this week in *Nature Astronomy*, the research builds upon earlier work with the Hubble Space Telescope, offering twice the resolution and a glimpse further back in time to approximately 8 to 10 billion years ago [[2]].
Scientists have created the most detailed map yet of dark matter, an invisible substance that makes up the majority of the universe’s mass, using observations from the James Webb Space Telescope. The map covers an area of the sky roughly three times the size of the full moon.
While ordinary matter – the stuff that makes up stars, planets, and everything we can see – accounts for only about 15% of the universe’s total matter, the remaining portion is dark matter. This enigmatic substance doesn’t emit or reflect light, making it invisible to both the human eye and traditional telescopes. Understanding dark matter is crucial to understanding the universe’s structure and evolution.
Scientists infer the presence of dark matter through its gravitational effects on visible matter, such as the rotational speeds of galaxies, how galaxies cluster together, and the bending of light from distant objects as it passes through massive cosmic structures. This latest research leverages the phenomenon of gravitational lensing to reveal the distribution of dark matter.
The new map was created by analyzing subtle distortions in the shapes of approximately 250,000 distant galaxies observed by the James Webb Space Telescope. These distortions are caused by the gravitational pull of dark matter along the line of sight. Previous dark matter maps were based on observations from the Hubble Space Telescope.
The Webb telescope’s enhanced capabilities deliver a map with twice the resolution of its predecessor, covering a larger area of the universe and peering further back in time – effectively observing the cosmos as it existed approximately 8 to 10 billion years ago, a pivotal period in galaxy formation.
“This allows us to find solutions for the finer structures of dark matter, discover concentrations of mass that were previously unseen, and extend the mapping of dark matter to earlier epochs of the universe,” said Diana Sconciamiglio, an astronomer at NASA’s Jet Propulsion Laboratory in California.
Sconciamiglio is a lead author of the research, published Monday in the scientific journal Nature Astronomy.
“A New Pair of Glasses to See the Universe”
The map reveals unprecedented detail of the universe’s large-scale structure, known as the cosmic web. This web consists of clusters of galaxies, vast filaments of dark matter along which galaxies and gas are distributed, and regions of lower density. Visualizing this structure provides key insights into how the universe evolved.
Launched in 2021 and operational since 2022, the James Webb Space Telescope operates in the infrared spectrum and possesses a light-gathering power approximately six times greater than that of the Hubble Space Telescope.
“The James Webb Telescope is like putting on a new pair of glasses to see the universe,” Sconciamiglio added. “It sees fainter and more distant galaxies with more clarity than ever before. This gives us a denser network of distant galaxies to work with, which is exactly what we want for this type of study. Detecting more galaxies and clearer images directly translates to a clearer map of dark matter.”
The map covers a portion of the sky known as the COSMOS survey, located in the direction of the Sextans constellation.
Researchers say the map will facilitate future explorations of the universe in numerous ways.
“One of the key questions in astrophysics is: how do galaxies grow and evolve over time? How did the universe transform from an almost perfectly uniform fluid into the amazing diversity of galaxies we see today?” said Jacqueline McCleary, an observational astronomer at Northeastern University in Boston.
McCleary added, “Dark matter halos – self-gravitating clouds of dark matter – are the sites of galaxy formation, or galaxy nurseries, if you will. So, knowing where dark matter is, how much there is, and linking it to the number of galaxies within the dark matter distribution puts an important constraint on models of galaxy formation and evolution.”
