Frozen space is world’s hottest spot for search for dark energy

Written by Staff Writer by By Rose-Marie Arbella, CNN Santiago, Chile

The Atacama Desert is one of the remotest places on Earth, and a hot bed of research into everything from infectious diseases to graphene. Scientists in Chile are now turning their attention to something else entirely: dark energy .

The region is a hotbed of research into dark energy, an inexplicable force thought to be accelerating the expansion of the universe, according to the Dark Energy Survey


Located in the north of Chile, the desert is part of a so-called cosmic microwave background “deposit” created by the first light from the Big Bang some 13.7 billion years ago. As this light cooled in the vast vacuum of space, it collected in massive fluctuations in the radio waves in our universe. Scientists believe this first radiation wave originated in the space between galaxies.

“The matter in space from the Big Bang was very hot, and so the early Universe was a very, very cold place,” Luis Murillo, of the Andean Observatory, explains. “The first light waves that reached Earth from those gas galaxies had to travel through the very cold cosmic microwave background.”

Researchers at the La Silla site, based in the Atacama desert. Credit: Juan Mascón/International Association of Research Authorities in Astronomy and Astrophysics

As the radio waves cooled further, they reached the bottom of space where they went dark. This led to the formation of the Cosmic Microwave Background radiation.

Mascón — who has been part of a team of scientists from 13 countries that have mapped the distribution of this relic radiation — wants to discover its contents.

But to begin with, he must allow elements from the background radiation to decays. For this, he and his colleagues rely on the Sillero wireless radio telescope system, launched in 1993. The first telescope on Earth to use this technology, Sillero is equipped with two radio antennas mounted on a three-meter-tall mountain.

“Every time, our laser detector sends the radio signal down, it travels into the interior of Sillero and gets an interference signal from the cosmic microwave background radiation,” explains Murillo.

“To measure the difference between the two, we use very precise amplifiers to make a radio signal — the signal of radio emissions from interstellar matter in our Universe — appear on the telescope in a structure of equal polarization.”

The measurements of this polarization map the radiation, allowing for the identification of sources. Credit: Javier Saenz

Harnessing the power of radio waves to find alien life

Sillero is the key to Sismol y Investigación General de la Astrophía (SIIAGAA), a collaboration between local and international scientists that hopes to more closely define the dark energy signature in the dark matter — the mysterious matter that makes up 75% of our universe.

“We want to create a very precise map of the dark energy in the cosmic microwave background,” explains Eduardo Purcell, of the Astrophysics and High Energy Institute at Nasa. “We really want to know about the sources, and are hoping that we can trace it to the Dark Energy Observatory.”

“The SISAL radio telescope is not designed to make any fundamental discovery,” he continues. “But it may be able to identify sources of dark energy of various components that have been detected by the Dark Energy Survey.”

Although it’s not very hard to find radio sources in the Atacama Desert — astronomers regularly record the sound of stars, electromagnetic signals emitted by planets, and communication from many different types of cosmic bodies — Jokes Purcell, “it is just hard to find them.”

Modest Size, Giant Potential

“For the Milky Way, the size of the universe is about 150 million light years,” he says. “I’m expecting to discover these dark energy sources within 10 million light years.”

The universe is thought to be composed of about 70% dark energy, according to NASA, and Dark Matter is said to account for about 25%.

“If we find a source on this boundary, we might find a lot of them,” says Purcell. “If we discover the source, it’s only natural to find them all over the galaxy.”

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