Scientists have identified faint radio signals emitted by the first stars shortly after they shined their light on the universe for the first time. The evidence suggests the earliest stars formed 180 million years after the Big Bang in a period of transition known as the cosmic dawn. “Finding this minuscule signal has opened a new window on the early universe,” Arizona State University researcher Judd Bowman told The Guardian. “It’s unlikely we’ll be able to see any earlier into the history of stars in our lifetime.”

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After the Big Bang, the universe existed primarily as a vast sea of hydrogen gas covered with radiation, which is still present in today’s universe. During what is known as the dark ages, gravity began to pull gas together into more dense formations, some of which collapsed inward to create the first massive blue stars. As the surrounding hydrogen gas became excited, it began absorbing radiation, leaving clues regarding the universe’s first stars. The challenge for scientists was pinpointing exactly where and how the weak radio signals would appear. “The team have to pick up radio waves and then search for a signal that’s around 0.01% of the contaminating radio noise coming from our own galaxy,” cosmologist Andrew Pontzen told The Guardian. “It’s needle-in-a-haystack territory.”

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The key to uncovering the clues is a small instrument known as The Edges (Experiment to Detect Global EoR Signature) antenna, which is located in remote Western Australia to avoid radio interference. The team documented their years-long process in a study published in the journal Nature, noting that hydrogen gas surrounding the early stars seemed to have lost heat at a faster rate than expected. A separate study concludes the hydrogen gas may have been losing heat to dark matter, which would suggest a new kind of interaction between ordinary matter and dark matter. Many questions remain about the mysterious matter. “We know so little about it that there are many theories as to what dark matter is,” astronomer Lincoln Greenhill told The Guardian. “Many may shortly be eliminated from the running.”

Via The Guardian

Images via NR Fuller/National Science Foundation