An array of 350 radio telescopes in South Africa’s Karoo desert is on the verge of detecting the “cosmic dawn” after the Big Bang, when stars first twinkled and galaxies began to bloom. A team of scientists from North America, Europe and South Africa has doubled the sensitivity of a radio telescope called the Hydrogen Re-ionization Array (HERA). Through this breakthrough, they hope to investigate the secrets of the early universe.

“For the past few decades, teams around the world have been working on the first detection of radio waves from a cosmic star. Associate Professor Adrian Liu of McGill University’s Department of Physics and the Trottier Space Institute said, “While such a detection is difficult, HERA’s results are today. “It represents the most accurate search ever.”

This array was already the world’s most sensitive radio telescope, designed to study the cosmic dawn. The HERA team increased its sensitivity by 2.1 times for radio waves emitted approximately 650 million years after the Big Bang and 2.6 times for radio waves emitted approximately 450 million years after the Big Bang. Their work is described in a published article. Astrophysical Journal.

While scientists have yet to detect radio emission from the end of the cosmic dark ages, their results provide clues about the composition of stars and galaxies in the early universe. Their data so far show that, unlike our present-day galaxies, early galaxies contained very few elements other than hydrogen and helium. Modern stars contain a variety of elements, from lithium to uranium, which is heavier than helium.

Except for some theories

Once the radio antennas are fully online and calibrated, the team hopes to create a 3D map of bubbles of ionized and neutral hydrogen (markers of the first galaxies) that evolved from about 200 million years to about 1 billion years after the Big Bang. According to the researchers, the map can tell us how the first stars and galaxies were different from what we see around us today, and what the universe looked like in our youth.

The fact that the HERA team has yet to detect these signals invalidates some theories about how stars evolved in the early universe, the researchers said. “Our data show that early galaxies were about 100 times brighter in X-rays than modern galaxies. That was thought to be the case, but now we have real data to support this hypothesis,” says Liu.

Waiting for a signal

The HERA team continues to refine the telescope’s calibration and data analysis in hopes of seeing these bubbles in the early universe. However, filtering out local radio interference to see signals from the early universe wasn’t easy. “If it’s Swiss cheese, galaxies are punching holes, and we’re looking for cheese,” says David DeBoer, a research astronomer at the UC Berkeley Radio Astronomy Laboratory.

“HERA continues to evolve and set better boundaries,” says Aaron Parsons, principal investigator for HERA and associate professor of astronomy at the University of California, Berkeley. “It’s great that we can keep moving forward and have new techniques for our telescope that continue to bear fruit.”