Dark matter from billions of years ago has finally been detected by scientists on Earth.
Researchers have been able to study the nature of the dark matter that surrounded galaxies as they were 12 billion years ago. It’s billions of years earlier than we’ve ever been able to see before.
Scientists hope these groundbreaking findings could unlock the secrets of the still-mysterious dark matter that makes up an important part of our universe but is largely unknown.
It has already offered tantalizing clues to the history of our cosmos. The researchers say the findings suggest that the fundamental rules of the universe were different in its early days.
As the name suggests, scientists are not able to see dark matter directly because it does not emit light. Instead, scientists typically watch light move through the galaxies they want to study, measuring how it travels – the more distorted it is, the more dark matter there is.
However, the most distant galaxies – which we see as they existed billions of years ago – are too faint for this technique to work. The distortion cannot be detected correctly and the dark matter remained impossible to analyze.
This has left scientists unable to search for dark matter from more than around 10 billion years ago. The time before and the beginning of the universe, 13.7 billion years ago, remained incomprehensible.
Today, scientists say they have overcome this problem by using a different source: the microwaves emitted by the Big Bang. The team measured how these microwaves were distorted, rather than light, and in doing so they were able to see dark matter from the beginnings of the cosmos, looking at galaxies shortly after they formed.
“Most researchers use source galaxies to measure the distribution of dark matter from the present to eight billion years ago,” added Assistant Professor Yuichi Harikane of the Cosmic Ray Research Institute. from the University of Tokyo. “However, we were able to look further into the past because we used the more distant CMB to measure dark matter. For the first time, we have been measuring dark matter since almost the earliest moments of the universe.
The results showed a series of surprises, including how dark matter clumped together in the early universe. The theory suggests that dark matter should clump together and form lumps in the cosmos – but there were far fewer than expected.
“Our discovery is still uncertain,” said Hironao Miyatake of Nagoya University, who led the team. “But if true, that would suggest the whole model is flawed as you go further back in time. That’s exciting because if the result holds after reducing uncertainties, that might suggest improvement. of the model that could provide insight into the nature of dark matter itself.
An article describing the results is published in Physical examination letters.