A new analysis of data from the James Webb Space Telescope (JWST) has provided a unique glimpse into the end of the cosmic Dark Ages, some 550 million years after the Big Bang. This is a period in which the universe transitions from a state in which light from stars was blocked by neutral atoms to an era in which it became possible to observe starlight. Despite the formation of the first stars and galaxies, their light initially remained invisible due to absorption by neutral atoms. The situation changed when these atoms began to ionize under the influence of ultraviolet radiation from massive, hot stars.
These stars, tens, hundreds, and even thousands of times more massive than the Sun, contributed to the ionization of hydrogen, which in turn led to the transparency of the universe to starlight. This ionization process was heterogeneous, depended on the distribution density of matter within the cosmic network, and lasted hundreds of millions of years. Some regions of the universe became transparent to visible light much earlier, while in other places neutral gas persisted for billions of years. JWST operates in infrared light, allowing astronomers to observe early galaxies and star systems that were not visible in visible light.
To date, JWST has discovered a record number of the most distant galaxies, black holes, galactic protoclusters, and quasars, opening new horizons for understanding the evolution of the universe. These discoveries not only support the formation of heterogeneous structures in the early universe, but also provide hope for the discovery of even earlier celestial bodies. The importance of these observations is that they reveal the role of the first stars and galaxies in the ionization of matter, which made the universe transparent to starlight of all wavelengths.