Scientists have for the first time detected the elusive forces that make up most of the universe —dark matter— from galaxies nearly 12 billion years away, making it the earliest detection of these mysterious substances.
The detection is groundbreaking since it’s extremely difficult to see these objects that emit no light.
Researchers at Nagoya University in Japan have published new findings in the journal Physical Review Letters that offer a new possibility, “that the fundamental rules of cosmology may differ when examining the early history of our universe.”
WHAT IS DARK MATTER?
Dark matter, according to Nasa, makes up most of the universe’s mass and creates its underlying structure. Dark matter’s gravity drives normal matter (gas and dust) to collect and build up into stars and galaxies. Scientists simply refer to it as the glue which holds our solar system, galaxies, and clusters of galaxies together.
While they are invisible, astronomers know it’s there because when they measure the stars and other regular matter in galaxies, they find that there is not nearly enough gravity to hold these clusters together meaning some invisible force at play.
FINDING DARK MATTER
A team of researchers from Nagoya University, the University of Tokyo, the National Astronomical Observatory of Japan, and Princeton University analyzed microwave light emanating from the Big Bang, which has been distorted by dark matter over billions of years.
They used the Subaru Hyper Supreme-Cam Survey (HSC) and identified 1.5 million lens galaxies using visible light, selected to be seen 12 billion years ago. They analysed the cosmic microwave background (CMB), fossil radiation left from the Big Bang, which is spread through the universe, and using microwaves observed by the European Space Agency’s Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.
“Look at dark matter around distant galaxies? It was a crazy idea. No one realized we could do this. But after I gave a talk about a large distant galaxy sample, Hironao came to me and said it may be possible to look at dark matter around these galaxies with the CMB,” Professor Masami Ouchi of the University of Tokyo said in a statement.
It is worth mentioning that the findings that we see today must have happened in space 12 billion years ago and it was the light from that event that reached us today. Because of the finite speed of light, we see distant galaxies not as they are today, but as they were billions of years ago.
The detection is difficult since galaxies in the deepest reaches of the universe are incredibly faint and the further away we look, the lensing distortion is subtle and difficult to detect in most cases, which does affect the calculations.
Researchers combined the data around the sample galaxies and the lensing distortions in CMB and found the invisible dark matter to be present even before in time when the universe was just in its infancy.
“I was happy that we opened a new window into that era 12 billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present; the first galaxy clusters are starting to form as well,” Hironao Miyatake from Nagoya University said.
The team now wants to look further back in the moments just after the big bang and look for dark matter.
