Unlocking the Mysteries of the Universe: the First Lights and the Age of Reionization

When we look at the sky, we see many luminous stars and galaxies, but how did it all begin?

When did the universe light its first lights? Scientists have long been asking this question, and only recently have been able to come close to answering it. Using the James Webb Space Telescope, they were able to get the most in-depth look at the period known as the Age of Reionization. In four separate articles accepted or published in The Astrophysical Journal, scientists have described in detail this enigmatic period in the history of our universe.

Period of the Age of Reionization

The early universe was a time of rapid change. Initially, the cosmos was filled with a hot, murky mist of ionized gas, which was impervious to light. As the gas began to cool, protons and electrons began to combine, forming mostly neutral hydrogen atoms and some helium. This period is called the Age of Recombination, and it occurred about 300,000 years after the Big Bang.

The next phase of the transition was reionization. Scientists believe that clumps of neutral hydrogen began to form stars clustered in galaxies by irradiating the gaseous medium with ultraviolet light. This reionized the gas, knocking out electrons. However, as space expanded slightly, the newly ionized hydrogen was scattered enough to continue to let light through. About 1 billion years after the Big Bang, space became completely transparent.

The Age of Reionization – A Mysterious Period

However, it is difficult to understand what was going on in the Age of Reionization. It is very far away, the objects are very dim, and there is still a lot of opaque space obscuring our view. But that’s where the James Webb Infrared Space Telescope, which was built with this period in mind, comes to the rescue. Its powerful gold-plated eye detects signals of objects shining in the distant darkness.

In a preprint accepted by The Astrophysical Journal, an international team of astronomers led by Pierluigi Rinaldi of the University of Groningen in the Netherlands reveals the first detection of the reionization epoch (EoR) of a particular wavelength of hydrogen, called hydrogen alpha. This discovery opens up new possibilities for studying this mysterious period in the history of the universe and understanding the processes that took place when everything was still something like a hot messy soup of matter.

Star formation in the early Universe

New observations from the James Webb Space Telescope show that star formation was widespread, and the light from this process played a significant role in clarifying the clouds of the early universe. These observations have helped scientists gain a better understanding of how stars and galaxies began to form in the early Universe.

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