Dwarf galaxies like lighthouses in the fog of the early universe

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Dwarf galaxies like lighthouses in the fog of the early universe

Small but powerful, the dwarf galaxies would have been the 'lighthouses' that cleared the hydrogen fog in the primordial universe 600-800 million years after the Big Bang, starting the so-called re-ionization era in which light started to spread. This is suggested by data from the James Webb space telescope, published in Nature by an international research group led by Hakim Atek of the Institute of Astrophysics in Paris.

Thanks to the powerful view of the telescope operated by the space agencies of Europe, the United States and Canada, researchers have obtained the first spectra of light emitted by dwarf galaxies close to the dawn of the cosmos. They succeeded thanks to a sort of cosmic magnifying glass, the Abel 2744 galaxy cluster, which generates a gravitational field so dense that it produces a curvature of space-time that distorts and enhances the light of distant galaxies behind it. , along the same visual line.

The results of the study show that the dwarf galaxies were one hundred times more numerous than the larger galaxies and collectively emitted four times as much ionizing radiation, more than was needed to clear the hydrogen fog that pervaded intergalactic space.
“Despite their size, these small galaxies are large producers of energetic radiation, and their abundance during this period is so substantial that their collective influence may have transformed the entire state of the universe,” explains Atek.

The study provides very solid evidence to reconstruct what happened in the so-called re-ionization era, but the researchers still intend to deepen their investigations to demonstrate that the sample of dwarf galaxies considered is truly representative of those that populated the dawn of the cosmos.

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