The moment when the first stars in the universe lit up the night sky, known as “cosmic dawn,” was detected by scientists this week in a “revolutionary” finding through a faint radio signal.
The signal suggests that the first stars were created about 180 million years after the big bang. Scientists from Arizona State University said in the paper — published in the journal Nature — that that the signal also contained evidence of the existence of dark matter, a potential second breakthrough into the history of the universe.
“Finding this minuscule signal has opened a new window on the early universe,” the study’s co-author Judd Bowman told The Guardian. “It’s unlikely we’ll be able to see any earlier into the history of stars in our lifetime.”
After the big bang, the universe was what scientists refer to as the Cosmic Microwave Background — a cold, dark void full of hydrogen gas and radiation, which still inhabits all of space. Over the next 100 million years, during the “dark ages,” more dense gasses were pulled into groups by gravity with some collapsing inwards and creating the first bright blue and short-lived stars. The surrounding hydrogen atoms then became “excited,” according to the study, and began to absorb the radiation from the CMB.
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The researchers used this information to predict that the cosmic dawn left an imprint of itself in the CMB radiation as a temporary lapse in brightness that should be still viewable today, in theory.
“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 at University College London, Andrew Pontzen, told the news site. “It’s needle-in-a-haystack territory.”
But the signal was detected over several years of research by Bowman and his colleagues with the help of a small, table-sized instrument called The Edges (Experiment to Detect Global EoR Signature) in Western Australia, where there are very few human-made radio waves around to interfere.
The findings of the experiment need to be replicated by an independent firm but the results are being described as “incredible.”
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“(It’s) an incredible achievement, constituting the first ever detection of the era of the first stars,” Royal Astronomical Society research fellow Emma Chapman told The Guardian.
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