Astronomers believe a new observation technique that relies on detecting weak radio signals will allow them to see the first stars that formed amid thick clouds of hydrogen shortly after the birth of the universe.
The technique, presented in a new paper, looks for a type of electromagnetic radiation signature known as the 21-centimeter line, which was emitted by hydrogen atoms that filled the young universe in the first hundreds of thousands of years after the big Bang.
The signal is extremely weak, about a hundred thousand times weaker than the radio signals emitted by objects in our galaxy, the Milky Way. Separating the signal from all other noise detected by the radio antennas will require complex data analysis.
“Our method jointly analyzes data from multiple antennas and over a wider frequency band than equivalent current instruments,” said Eloy de Lera Acedo, an astronomer at the University of Cambridge in the UK and lead author of the new paper. statement (opens in a new tab).
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By measuring the contrast between the radiation from hydrogen clouds and the signal behind them, astronomers hope to “see” the stars as if they were “shadows in the fog”.
“At the time the first stars formed, the universe was essentially empty and composed mostly of hydrogen and helium,” de Lera Acedo said in the statement. “Due to gravity, the elements finally came together and the conditions were right for nuclear fusion, which formed the first stars. But they were surrounded by clouds of so-called neutral hydrogen, which absorb light very well. , so it is difficult to directly detect or observe the light behind the clouds.”
The James Webb Space Telescope, which recently released its first science-grade images, is also looking for the first light in the universe, but using a different technique. Webb detects infrared radiation, which is basically heat. Since heat can penetrate dust clouds, Webb also allows astronomers to peer into the universe’s most impenetrable regions.
The new radio astronomy method was developed as part of the REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) project and builds on previous observations that hinted at the detection of the 21 centimeter line. These earlier measurements, however, could not be replicated, leading scientists to believe the signal could be an error.
“If we can confirm that the signal found in this earlier experiment really came from early stars, the implications would be huge,” said de Lera Acedo.
The researchers used simulations mimicking real observations using multiple radio antennas, which improved the reliability of the data compared to previous measurements relying on a single antenna.
The new measurements will be taken later this year at Karoo in South Africa.
“We are extremely excited to see how well the system will perform and are fully confident that we will make this elusive detection,” said Dirk de Villiers, radio astronomer at the University of Stellenbosch in South Africa and co-author. principal of the new paper, said in the statement.
Scientists have previously detected signals from the Big Bang in the form of the cosmic microwave backgroundbut the emergence of the first stars in the universe after the dark ages of its first hundred thousand years is still a missing piece.
The paper (opens in a new tab) was published in the journal Nature Astronomy on Thursday July 21.