Astronomers using the Hubble and James Webb telescopes discover that faint, low-mass galaxies were able to reionize intergalactic gas in the early universe, requiring little ultraviolet light to escape from the galaxy. did. This paper was published in the journal Nature. The Reionization Era occurred 600 million to 800 million years after the Big Bang, when the neutral hydrogen that filled the universe during the Dark Ages was reionized by ultraviolet radiation from the first stars and galaxies. At the same time, the question of how different radiation sources such as quasars, bright galaxies, and low-mass galaxies contribute to the ionization of the gas remained a matter of debate. The ability of galaxies to reionize the universe depends on the density of ionizing photons they produce per unit time and the proportion of this radiation used to ionize intergalactic gas. A team of astronomers led by Hakim Atek of the Paris Institute of Astrophysics has published the results of a study of eight ultrafaint galaxies that are candidates for reionization-era galaxies. The target was selected based on observations of the Abell 2744 galaxy cluster by the Hubble and James Webb telescopes. This galaxy cluster acts as a gravitational lens for galaxies behind the cluster. Selected targets were examined spectroscopically using James Webb. The eight galaxies have spectral redshifts between z=6 and 7.7 and absolute magnitudes between 17 and 15. They are characterized by very low stellar masses (105.88 – 107.12 solar masses), small amounts of dust, and a population of very young massive stars that are several million years old. To date, most reionization models account for a large portion of the radiation coming out of galaxies (usually about 20%), but for the selected galaxies this value was more than 5%. (the number of ionizing photons per unit of ultraviolet luminosity density galaxy) was found to be four times larger than typical values. If these results can be extended to large-scale distributions of faint galaxies, such a system could potentially produce enough ionizing photons to support the Milky Way. Reionization of intergalactic gas near z 7

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