In 2018, astronomers operating an antenna called EDGES in the Australian outback reported that radio waves of a particular frequency were significantly dimmer than other waves coming from the night sky. The finding, published in Nature, was heralded as a groundbreaking signal from the birth of the first stars after the Big Bang — an event dubbed “cosmic dawn,” which should have stamped such a signature in the light.
What’s more, the dip in the radio spectrum observed by EDGES looked strikingly different than cosmologists had predicted. The data suggested that the early universe was surprisingly cold, triggering much theoretical activity and attempts to confirm the signal by other astronomers around the world.
Today, one such team, at the Raman Research Institute in Bangalore, India, has published the result of its search for the EDGES dip using a radio antenna called SARAS. The astronomers set the antenna afloat on a pair of remote lakes in India in early 2020, cutting their data collection short and returning to Bangalore hours before the first citywide COVID lockdown began. After spending the pandemic analyzing their data, the SARAS team now reports in Nature Astronomy that they found no trace of the dip observed by EDGES.
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