Amazingly, science has recently unraveled a secret of “dark matter,” a mysterious, invisible substance making up most of the universe. Using data from NASA’s James Webb Space Telescope (JWST), scientists have made one of the most detailed, high-resolution maps of dark matter ever produced. The study was published in the journal Nature Astronomy last Monday, on January 26.
Although dark matter does not make itself visible, it plays a very important role in giving galaxies in our universe extra mass, as theorized by scientists. This generates extra gravity needed to keep galaxies intact. If dark matter did not exist, these galaxies would have torn themselves apart long ago; they are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together.
“This is the largest dark matter map we’ve made with Webb, and it’s twice as sharp as any dark matter map made by other observatories,” said Diana Scognamiglio, lead author of the paper and an astrophysicist at NASA’s Jet Propulsion Laboratory in Southern California. “Previously, we were looking at a blurry picture of dark matter. Now we’re seeing the invisible scaffolding of the universe in stunning detail, thanks to Webb’s incredible resolution.”
Found in the constellation Sextans, the area covered by the map is a section of sky about 2.5 times larger than the full Moon. The JWST peered at this region for a total of about 255 hours and identified nearly 800,000 galaxies, some of which were detected for the first time. Scognamiglio and her colleagues then looked for dark matter by observing how its mass curves space itself, which in turn bends the light traveling to Earth from distant galaxies. When observed by researchers, it’s as if the light of those galaxies has passed through a warped windowpane!
The map illustrates the degree of overlap between dark matter and regular matter. The findings indicate that dark matter interacts with the universe through gravity, clearer than ever before.
“Wherever we see a big cluster of thousands of galaxies, we also see an equally massive amount of dark matter in the same place. And when we see a thin string of regular matter connecting two of those clusters, we see a string of dark matter as well,” said Richard Massey, an astrophysicist at Durham University in the United Kingdom and a coauthor of the new study. “It’s not just that they have the same shapes. This map shows us that dark matter and regular matter have always been in the same place. They grew up together.”
According to the paper’s authors, the JWST’s observations confirm that this close alignment cannot be a coincidence but, rather, is due to dark matter’s gravity pulling regular matter toward it. The map demonstrates that dark matter and ordinary matter always co-existed and evolved together throughout cosmic history.
Dark matter determined the large-scale distribution of galaxies in the universe. Additionally, by prompting galaxy and star formation to begin earlier than they would have otherwise, dark matter’s influence also played a role in creating the conditions for complex planets to eventually form.
“This map provides stronger evidence that without dark matter, we might not have the elements in our galaxy that allowed life to appear,” said NASA’s JPL (Jet Propulsion Laboratory) astrophysicist Jason Rhodes. “Dark matter is not something we encounter in our everyday life on Earth, or even in our solar system, but it has definitely influenced us.”
