Signals have been detected from stars that were born just 180 million years after the Big Bang.
What were these first stars, how and when did they form? How did they affect the rest of the universe? These are questions that astronomers and astrophysicists have pondered over the years.
It is believed that a long time ago, about 400,000 years after the Big Bang, the universe was dark. There were no stars or galaxies, and space was filled with neutral hydrogen gas. Then, over the next 50-100 million years, gravity slowly collected dense clouds of gas, which eventually began to collapse and form stars. But now it looks like history will have to be rewritten.
In a new study, published in the journal Nature, an international team of scientists reports the detection of signals from stars that were born just 180 million years after the Big Bang.
“The discovery, which we have been pursuing for 12 years, was a great technical breakthrough. A small radio antenna in the desert has seen farther than the most powerful space telescopes, opening a new window to the early universe for us. In the study, we had to separate the noise from the true signal, which in some cases was a thousand times weaker than interference. It's like trying to hear the sound of a hummingbird flapping in the middle of a hurricane,”says Peter Kurczynski, a National Science Foundation researcher who took part in the study.
It is assumed that the first stars were massive and died very quickly. Although they emitted a lot of ultraviolet light, they are too weak for current telescopes such as the Hubble. But astronomers have suggested that these firstborns may be indirectly indicated by dips in the cosmic background radiation - the afterglow of the Big Bang, which occurred 13.8 billion years ago. These dips create a clear radio signal associated with the absorption of background radiation by the hydrogen gas.
An updated timeline of the Universe showing stars born 180 million years after the Big Bang. Credit: NRFuller, National Science Foundation.
To find the signatures of the first stars in the universe, the team used a ground-based radio spectrometer located at the Murchison Radio Astronomy Observatory in Western Australia. After a year of detector calibration, the researchers found what they were looking for. They detected a signal with a frequency of 78 MHz, which, according to theorists, lies in the range associated with star formation 180 million years after the birth of the universe.
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Unexpected results
The results of the experiment carried out confirm the theoretical assumptions describing the birth time of the first stars and their main properties, but they raise new questions.
The study showed that the gas in the universe was much colder than expected - about -270 degrees Celsius. This suggests that either astrophysicists are missing out on something significant, or this may be the first evidence of non-standard physics, in particular, the interaction of baryons (normal matter) with dark matter in the young universe.
“We may have learned something new and fundamental about the mysterious dark matter, which makes up 85 percent of all matter in the universe, and got a first look at physics beyond the standard model,” concluded Judd Bowman, lead author of the study at Arizona State University. USA).
Roman Zakharov