Israeli, US Astronomers Discover First Signs Of Dark Matter While Searching For Earliest Stars

By NoCamels Team March 01, 2018 2 minutes

This collage shows NASA/ESA Hubble Space Telescope images of six different galaxy clusters. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. Wikimedia

Israeli and American scientists revealed this week that they have found the first, direct signs of the existence of dark matter, believed to make up some 80 percent of the mass of the universe. The matter does not emit light or energy and is considered one of the greatest mysteries in physics.

The discovery was made while the scientists, a team of astronomers led by Professor Judd Bowman of Arizona State University, were attempting to detect the earliest stars in the universe through radio wave signals.

The findings were published in science magazine Nature this week, by Professor Rennan Barkana, the head of the Department of Astrophysics at Tel Aviv University’s School of Physics and Astronomy. The signal picked up by the astronomers, recorded by a novel radio telescope called EDGES, dates to 180 million years after the Big Bang, according to a TAU statement.

An illustrative photo of the galaxy. Pexels

“Professor Bowman and his colleagues reported the detection of a radio wave signal at a frequency of 78 megahertz. The width of the observed profile is largely consistent with expectations, but they also found it had a larger amplitude (corresponding to deeper absorption) than predicted, indicating that the primordial gas was colder than expected,” the statement read.

“I realized that this surprising signal indicates the presence of two actors: the first stars, and dark matter,” Professor Barkana said. “The first stars in the universe turned on the radio signal, while the dark matter collided with the ordinary matter and cooled it down. Extra-cold material naturally explains the strong radio signal.”

Based on the radio signal, Professor Barkana said that, unlike previous beliefs by physicists that dark matter particles would be heavy, the discovery indicates that they are no heavier than several proton masses, low-mass particles. “This insight alone has the potential to reorient the search for dark matter,” he said.

The professor added that “dark matter is the key to unlocking the mystery of what the universe is made of.”

“We know quite a bit about the chemical elements that make up the earth, the sun and other stars, but most of the matter in the universe is invisible and known as ‘dark matter.’ The existence of dark matter is inferred from its strong gravity, but we have no idea what kind of substance it is. To solve it, we must travel back in time. Astronomers can see back in time, since it takes light time to reach us. We see the sun as it was eight minutes ago, while the immensely distant first stars in the universe appear to us on earth as they were billions of years in the past,” said Barkana.