Dark matter 12 billion years ago mapped through warped spacetime

Embedded in our universe lies one of the greatest unsolved mysteries of science. Where’s all the dark matter? What is everything dark matter?

I mean we know it’s there.

Galaxies, including the Milky Way, spin so fast that our physics predict that everything inside should be spun outward like horses on an out of joint merry-go-round. But obviously that’s not happening. You, me, the sun and the earth are anchored securely. So scientists theorize that something – probably shaped like a halo – must surround galaxies to keep them from falling apart.

Whatever encompasses these boundaries is called dark matter. We can’t see it, we can’t feel it, and we don’t even know if it is one thing. It’s the epitome of elusive. All we know is that dark matter exists.

Despite our inability to see or touch the material ourselves, experts have interesting ways of identifying the impact it is having on our universe. After all, we deduced the presence of dark matter in the first place by noticing how it holds galaxies together.

Scientists took advantage of this principle and on Monday announced remarkable new insights into dark matter. Armed with a toolbox of warped space, cosmic remnants of the Big Bang, and powerful astronomy instruments, they discovered a deep-space zone of previously unstudied dark matter halos — each arranged around an ancient galaxy, dutifully protecting it from a merry-go-round nightmare.

These vortices are from the past, according to a study of the find published in Physical Review Letters 12 billion years, nearly two billion years after the Big Bang. That could very well make them the youngest rings of dark matter ever studied by mankind, the authors suggest, and potentially the start of the next chapter in cosmology.

“I was glad that we opened a new window into this era,” said Hironao Miyatake, of Nagoya University and author of the study, in a statement. “It was very different 12 billion years ago. You can see more galaxies in the process of formation than today, and the first clusters of galaxies are also beginning to form.”

Wait, warped space? Cosmic Residue?

Yes, you read that correctly. Let’s explain.

When Albert Einstein coined his famous general theory of relativity more than a century ago, one of his predictions was that super-strong gravitational fields emanating from vast amounts of matter would literally warp the fabric of space and time, or space-time. He turned out to be right. Today, physicists exploit the concept using a technique called gravitational lensing to study very distant galaxies and other phenomena in the Universe. It works something like this.

Imagine two galaxies. Galaxy A is in the background and B is in the foreground.

Essentially, when light from galaxy A passes galaxy B to get to your eyes, that luminescence is distorted by B’s matter, dark or not. This is good news for scientists, as such distortions are common enlarged distant galaxies, a kind of lens.

Also, there’s a kind of back calculation you can do with this light distortion to find out how much dark matter surrounds Galaxy B. If Galaxy B had one a lot of of dark matter, you would see a a lot of more distortion than expected from visible matter – the stuff we can see – inside. But if it didn’t have so much dark matter, the distortion would be much closer to your prediction. This system has worked fairly well, but it has a caveat.

Standard gravitational lensing only allows researchers to identify dark matter around galaxies a maximum of about 8 to 10 billion light-years away.

This is because visible light becomes increasingly difficult to interpret the deeper you look into the universe, eventually even turning into infrared light that is completely invisible to the human eye. (That’s why NASA’s James Webb Space Telescope is such a big deal. It’s our best shot at catching the faintest, most invisible light that comes from the distant cosmos.) However, this means that visible light distortion signals for dark matter studies fade much past a certain point to help us analyze the to help hidden material.

Miyatake found a workaround.

Maybe we can’t see standard light distortions to detect dark matter, but what if we can see a different kind of distortion? As it turns out, there is: Microwave radiation released from the Big Bang. It’s pretty much Big Bang thermal residue officially known as cosmic microwave background or CMB radiation.

“Looking at dark matter in distant galaxies?” Masami Ouchi, a cosmologist at the University of Tokyo and a co-author of the study, said in a statement. “It was a crazy idea. Nobody knew we could do that. But after I gave a talk about a large distant sample of galaxies, Hironao came to me and said it was possible to study dark matter around these galaxies with the CMB. ”

Essentially, Miyatake wanted to observe how dark matter directed our universe’s first light through gravitational lenses.

Collect pieces of the Big Bang

“Most researchers use source galaxies to measure the distribution of dark matter from the present to 8 billion years ago,” said Yuichi Harikane, an assistant professor at the University of Tokyo and a co-author of the study, in a statement. “However, we were able to look further back in time because we used the more distant CMB to measure dark matter. For the first time we have measured dark matter from almost the earliest moments of the universe.”

To arrive at their findings, the new study team first collected data from observations from the Subaru Hyper Suprime-Cam Survey.

This led them to identify 1.5 million lensed galaxies – a cluster of hypothetical galaxies B – that could be traced back to 12 billion years ago. They then requested information from the European Space Agency’s Planck satellite about the microwave radiation from the Big Bang. Putting it all together, the team could figure out if and how these lensing galaxies distort the microwaves.

“This result gives a very consistent picture of galaxies and their evolution, as well as the dark matter in and around galaxies and how that picture evolves over time,” Neta Bahcall, professor of astrophysical sciences at Princeton University and co-author of the study, said in a statement.

Remarkably, the researchers highlighted their study, in which they found that dark matter from the early Universe does not appear to be as clumpy as our current physics models suggest. Across the board, this bit could adjust what we currently believe about cosmology, mostly theorems rooted in the so-called lambda CDM model.

“Our finding is still uncertain,” said Miyatake. “But if it’s true, going further back in time would suggest that the entire model is flawed.” This is exciting because if the result holds after the uncertainties have been reduced, it could indicate an improvement in the model that could provide insights into the nature of dark matter itself.”

Next, the study team plans to explore even earlier regions of space, using information from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time.

“LSST will allow us to observe half the sky,” Harikane said. “I see no reason why we couldn’t see the distribution of dark matter 13 billion years ago.”