The cosmological radio signal will help astronomers to detect first generation stars of the universe
The first generation of stars (population III) must have been formed from the uninichi gas which has permeated the universe of the infant. These stars produced the first heavier and reilluminized elements the universe, thus ending the ages of cosmic darkness and inaugurating the universe in the era of reionization. Due to a lack of direct observations, the properties of the first stars remain very uncertain. According to Professor Anastasia Fialkov of the University of Cambridge and his colleagues, astronomers will be able to learn more about the masses of these stars by studying the cosmological signal of 21 cm – created by hydrogen atoms filling the gaps between the stars formation regions – of origin only a hundred million years after the Big Bang.
The impression of this artist shows an area of the stars of the population III because they would have appeared only 100 million years after the Big Bang. Image credit: Noillab / NSF / AURA / J. DA Silva / SpaceEngine.
“It is a unique opportunity to learn how the first light in the universe emerged from the dark,” said Professor Fialkov.
“The transition from a cold and dark universe to a star is a story that we are starting to understand.”
The study of the oldest stars in the universe depends on the low signal of the 21 cm signal, a subtle energy signal more than 13 billion years ago.
This signal, influenced by the influence of the first stars and black holes, provides a rare window on the childhood of the universe.
Professor Fialkov leads the theoretical scope of scope (the radio experience for the analysis of cosmic hydrogen).
“Reach is a radio antenna and is one of the two main projects that could help us discover the cosmic dawn and the era of reionization, when the first stars have reionized neutral hydrogen atoms in the universe,” said astronomers.
“Although Reach, which captures radio signals, is still in its calibration phase, it promises to reveal data on the early universe.
“Meanwhile, the square kilometer table (SKA) will map the fluctuations in cosmic signals in large regions of the sky.”
“The two projects are essential to probe the masses, the luminosities and the distribution of the first stars in the universe.”
In this study, Professor Fialkov and the co-authors have developed a model that makes predictions for the 21 cm signal for scope and ska, and found that the signal is sensitive to the masses of the first stars.
“We are the first group to systematically model the dependence of the 21 cm signal from the masses of the first stars, including the impact of ultraviolet light star and X -ray emissions from binary rays produced when the first stars die,” said Professor Fialkov.
“These ideas are derived from simulations which integrate the essential conditions of the universe, such as the composition of hydrogen-helium produced by the Big Bang.”
By developing their theoretical model, researchers have studied how the 21 cm signal reacts to the mass distribution of the stars of the population III.
They found that previous studies underestimated this link because they did not take into account the number and the brightness of binary X-rays among the stars of the population III, and how they affect the 21 cm signal.
Reach and Ska will not be able to imagine individual stars, but will rather provide information on entire populations of stars, binary X -ray systems and galaxies.
“It takes a little imagination to connect radio data to the history of the first stars, but the implications are deep,” said Professor Fialkov.
“The predictions we point out have enormous implications for our understanding of the nature of the very first stars of the universe,” said Dr. Eloy de Lera of the University of Cambridge.
“We show evidence that our radio stations can tell us about the mass of these first stars and how these first lights may have been very different from today’s stars.”
“Radiotelescopes like Reach promise to unlock the mysteries of the infantile universe, and these predictions are essential to guide the radio observations that we make of Karoo, South Africa.”
The newspaper was published today online in the journal Natural astronomy.
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T. Gessey-Jones and al. Determination of the mass distribution of the first stars of the 21 cm signal. Nat Astronpublished online on June 20, 2025; DOI: 10.1038 / S41550-025-02575-X
