The mystery of how the Universe became filled with cosmic light remained unsolved for a long time. Thanks to the power of the James Webb Space Telescope (JWST), an international team of scientists has finally found the answer. Despite their tiny size, it is dwarf galaxies that have turned out to be the powerful “energy centers” that illuminate our cosmic environment.
After the Big Bang, the Universe was a super-hot, dense plasma with no way for light to get through. It took several hundred thousand years for space-time to become transparent, but there were still no sources of light. The first stars born from this gas began to emit intense radiation capable of splitting hydrogen back into ions and electrons. This process, known as cosmic reionization, ended after a billion years, when the Universe finally became transparent to light. But who was the main “architect” of this transformation?
For a long time, scientists assumed that reionization was caused by powerful sources: massive galaxies with active star formation or even supermassive black holes. However, data from James Webb has radically changed this picture. It turned out that the real “culprits” were numerous dwarf galaxies, which had previously gone unnoticed due to their dimness and enormous distance.
Revealing the secret
A team led by astrophysicist Hakim Atek from the Institute of Astrophysics in Paris studied the galaxy cluster Abell 2744. Its gravity acts like a cosmic lens, magnifying light from more distant objects. This effect made it possible to see the tiniest galaxies of the cosmic dawn era. Detailed spectral analysis of these objects has shown that they are not only the most common in the early Universe, but also produce enormous amounts of ionizing radiation.
Revolution in understanding space
A study published in early 2024 reveals impressive figures: dwarf galaxies outnumber large galaxies by a ratio of 100:1. Their combined power is four times greater than the ionizing radiation previously attributed to large galaxies. Despite their small size, their sheer number made them a key force capable of changing the state of the entire Universe.
This discovery is just the beginning. Astrophysicists have studied only a small section of the sky, so the next step will be to search for similar dwarf galaxies in other regions to confirm that this is not a local anomaly.
Earlier, we reported on how James Webb studied the “lunch menu” of a white dwarf.
According to sciencealert.com
