Nasa’s new dark matter map

A new high-resolution map of distant galaxies may finally help scientists understand a mysterious substance that binds the universe together.

Taken by Nasa’s James Webb Space Telescope, the latest images, published as part of a study in the journal Nature Astronomy, include information on new galaxy clusters dating back 10 billion years and, crucially, the strands of so-called “dark matter” that connect them.

‘Getting closer to unmasking dark matter’

Dark matter is “one of the most persistent and important puzzles in all of physics”, said Elizabeth Landau in National Geographic.

While ordinary matter – stars, planets, people, basically anything the eye can see – makes up just 5% of the universe, dark matter comprises over a quarter, with “dark energy”, a mysterious but constant force which pushes stars and galaxies away from each other, making up the rest.

Dark matter “doesn’t have much of an impact on your midday lunch order or your nightly bedtime ritual”, said Adithi Ramakrishnan, science reporter at The Associated Press, “but it silently passes through your body all the time and has shaped the universe.”

The problem is that it “doesn’t absorb or give off light so scientists can’t study it directly”. Instead, they have to observe “how its gravity warps and bends the star stuff around it – for example, the light from distant galaxies”. Only by studying these distortions across large swathes of the universe, can scientists “get closer to unmasking dark matter and its various hiding places”.

‘Gravitational scaffolding into which everything else falls’

The new images made with the Webb telescope are “twice as sharp as any dark matter map made by other observatories,” said Diana Scognamiglio of Nasa’s Jet Propulsion Laboratory and lead author of the study.

Building on previous observations made using the Hubble Space Telescope, the new map “reveals dark matter’s influence on the largest objects in the universe, like galaxy clusters stretching millions of light years across”, said BBC Sky at Night. It shows “the overlap between dark matter and regular matter, confirming dark matter’s role in pulling regular matter together throughout the history of the universe”.

The findings “reinforce scientists’ current theory” that the gravity of dark matter “pulled ordinary matter into clumps that grew into the first structures in the universe”, said National Geographic.

“It's the gravitational scaffolding into which everything else falls and is built into galaxies. And we can actually see that process happening in this map,” said Richard Massey, study co-author and physicist at Durham University.

This matters because without it “there wouldn’t be enough matter to gravitationally bind galaxies together, and our Milky Way galaxy, housing billions of planets including Earth, would not exist in its current form”, said National Geographic.

Scientists are now using the high-res images to develop a three-dimensional version of the map, which they hope will unlock the properties of dark matter itself.