A plausible explanation for light signals from the early universe has been found
The hydrogen flicker in the galaxies of the early Universe, which has long stumped scientists, may have finally been explained. Observations by NASA's James Webb Space Telescope (JWST) suggest that the cause of these light signals is faint galaxies colliding with each other.
This is stated in a study published in the journal Nature Astronomy. Scientists know that the early Universe, within 1 billion years after the Big Bang, was filled with pure gas, which should have blocked the abundant light emitted by hydrogen atoms. However, scientists saw exactly this kind of flickering in many early galaxies over and over again. This type of light was eventually called the Lyman alpha radiation but scientists did not understand why it occurred.
Now the authors of the new study are closer to solving this cosmic mystery.
Callum Witten of the University of Cambridge and his colleagues analyzed JWST images of nine distant galaxies that emitted Lyman alpha radiation. It turned out that each of these galaxies had a smaller one next to it. No one had ever noticed this before because these secondary galaxies are too faint to be seen with previous generations of telescopes.
The observations also revealed that these galaxies are most likely merging with their larger and brighter partners.
In the process of such mergers, bursts of star formation and light, including the Lyman alpha radiation, occur.
In addition, this process leads to the emergence of powerful winds that are quite capable of blowing away cosmic galactic gas, opening "gaps" for light to escape.
Scientists also suggest that such winds may well deprive gas atoms of electrons that would help absorb light.
Witten said that scientists had previously assumed that they did not see fainter galaxies in the early Universe but they also did not suspect that there would be so many of them and that they would be so close to these bright galaxies, contributing to the "leakage" of Lyman alpha radiation.
The researchers' simulations confirmed that the interaction between galaxies can indeed create channels in the gas that allow hydrogen emission to flow out in a way that our telescopes can detect.
However, they warn that the study of only 9 galaxies is not sufficient to draw definitive conclusions about the source of the Lyman radiation. In particular, there is a theory that turbulence from active black holes in the centers of these galaxies may also contribute to it.
Witten and his colleagues intend to study the new JWST data on more Lyman alpha emitters when they become publicly available.