JAKARTA – Astronomers have discovered a new way to ‘see’ through the haze of the early universe to detect the first light from stars and galaxies.
Observing the birth of these objects has long been a goal of scientists because it will help explain how the universe evolved after the Big Bang and the complex universe we see today, or 13.8 billion years later. This is something commissioned by the new James Webb Space Telescope.
But when Webb sees wavelengths in the infrared, the SKA telescope (square kilometer array) The Next Generation Earth-Based – due to be completed by the end of this decade – will study the early universe via radio waves.
For today’s radio telescopes, the challenge is to detect the star’s cosmological signal through dense clouds of hydrogen, which block view because it absorbs light so well.
Distortion from other radio signals can also get in the way, which is considered one of the extreme challenges facing modern radio cosmology.
For example, the signals from distant galaxies that astronomers are trying to detect are about 100,000 times weaker than in our own galaxy.
But researchers led by the University of Cambridge have now developed a new method, using mathematics, that allows them to see through ancient clouds and other sky noisy signals.
It would therefore allow them to avoid the harmful effects of distortion introduced by radio telescopes.
His idea, which was part of the REACH experiment (Radio experiments to analyze cosmic hydrogen), will allow astronomers to observe early stars through their interactions with hydrogen clouds, the same way we infer landscapes by looking at shadows in fog.
The hope is that this will improve the quality and reliability of observations from radio telescopes given this key, unexplained time in the evolution of the universe. The first observations from REACH are expected later this year.
“By the time the first stars formed, the universe was largely empty and made up mostly of hydrogen and helium,” said study lead author Dr. Eloy de Lera Acedo from Cambridge’s Cavendish Laboratory. daily mail,
“Because of gravity, the elements eventually came together and the conditions were just right for nuclear fusion, which formed the first stars,” he said.
“But they are surrounded by a cloud called neutral hydrogen, which absorbs light so well, it is difficult to detect or observe the light directly behind the cloud.”
In 2018, another research group published results pointing to a possible detection of this early light, but astronomers were unable to replicate it, leading them to believe the original result may have been due to interference from the telescopes used. .
“New physics will be needed to explain the original results, given the temperature of hydrogen gas, which must be much colder than our current understanding of the universe,” said Dr. de Lera Acedo.
“If we can confirm that the signal detected in the previous experiment did indeed come from the first star, the implications would be enormous,” he said.
To study this period of the universe’s evolution, often called cosmic dawn, astronomers used a 21-centimeter line, a sign of electromagnetic radiation from hydrogen in the early universe.
They looked for radio signals that measured the difference between the radiation from hydrogen and the radiation behind the hydrogen fog.
The method developed by Dr. de Lera Acedo and colleagues uses Bayesian data to detect cosmological signals in the presence of interference from telescopes and normal noise from the sky, in order to separate the signals.