Physicists Find Oldest Dark Matter Yet With Microwave Lens

Researchers have just studied the oldest lensing of light we can see and found the oldest dark matter ever observed, around a galaxy 12 billion years old.

They spotted this dark matter by looking at how some galaxies bend the cosmic microwave background light, the earliest detectable radiation after the Big Bang, that rocked the universe as we know it. The team’s research is published in Physical Review Letters.

“Most researchers use source galaxies to measure the distribution of dark matter from now to eight billion years ago,” said Yuichi Harikane, astronomer at the Institute for Cosmic Ray Research at the University of Tokyo and co-author of a recent paper, in a Nagoya University release. . “However, we were able to look further into the past because we used the CMB further afield to measure dark matter. For the first time, we’re measuring dark matter almost from the early days of the universe.”

Dark matter makes up about 27% of the universe, although we cannot detect it directly. Since we don’t know what it is, dark matter is really an umbrella term for this incalculable mass, which we see on a large scale thanks to its gravitational effects.

Some of the prime candidates for dark matter are tiny particles called WIMPs (Weakly Interacting Massive Particles) and even smaller particles called axions; it is very likely that WIMP and axion are dark matter. The search for dark matter is ongoing, but in the meantime, astronomers can search and see its effects on a large scale.

Dark matter acts as a kind of invisible glue, holding clusters of galaxies together. It also acts as a lens for more distant light, magnifying ancient objects for our observation. Although it is an enigma, dark matter is also an advantage for studying the early universe.

That’s why, when the Webb telescope recently imaged the galaxy cluster SMACS 0723, it actually saw all of the more ancient galaxies that SMACS 0723 magnified, including the most ancient galaxy ever seen, which formed 300 million years after the Big Bang.

Previous work has generally looked at shorter wavelengths through a gravitational lens, mostly objects at visible and infrared wavelengths. But the light we see from the cosmic background — the oldest light we can see — is in the microwave part of the electromagnetic spectrum. This light was initially very energetic, but was extended over time by the expansion of the universe, and today we see it as only a faint microwave light.

In recent work, researchers identified 1.5 million lens galaxies in visible light. They then looked at them using a telescope that looks at microwave light – ESA’s Planck satellite – and measured how much the dark matter around closer galaxies distorted the more ancient microwave light.

“These results provide a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies, and how these images evolve over time,” said study co-author Neta Bahcall, an astronomer at Princeton University, in the same release.

The team also found that dark matter in certain regions of space was less agglomerated than it should be according to standard cosmological theory.

“Our findings are still uncertain,” said Hironao Miyatake, astronomer at Nagoya University and lead author of the paper, in the release. “But if it were true, it would show that the whole model is flawed as you go further into the past. This is interesting because if the results hold up after the uncertainty is reduced, it could suggest model improvements that could provide insight into the nature of dark matter itself.”

In the future, data from the upcoming Rubin Observatory will help with imaging large parts of the night sky at a resolution that will make it easier to see more ancient parts of space.

Read more: The World’s Largest Digital Camera Is Almost Ready To Look To The Past

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Editor’s Note: The release dates in this article are based in the US, but will be updated with local Australian dates as we learn more.

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