Scientists have long puzzled over how the Universe shed its “fog” of ionized plasma, allowing light to shine through. Now, data from the Hubble and James Webb Space Telescopes reveals that small dwarf galaxies were responsible for this process.
The discovery, published in February 2024, shows that these tiny galaxies produced enough ionizing photons to transform neutral hydrogen into ionized plasma during the cosmic dawn. This period, occurring around 300,000 years after the Big Bang, marked a critical moment in the Universe’s evolution.
The research team, led by astrophysicist Hakim Atek of the Institut d’Astrophysique de Paris, used JWST data to analyze galaxies in the Abell 2744 cluster. They found that dwarf galaxies outnumber large galaxies by 100 to 1 and emit four times more energy than initially assumed.
The implications are significant: these low-mass galaxies played a crucial role in shaping the Universe’s history. With this breakthrough, scientists have finally begun to peel away the fog surrounding reionization, a process that has long been a subject of mystery.
Source: https://www.sciencealert.com/we-now-know-what-switched-the-lights-on-at-the-dawn-of-time