Using the Chile-based Very Large Telescope (VLT), a group of international astronomers was able to produce the first timeline of what happened during a time in the Universe's history known as the reionization epoch. For starters, the team learned that this event occurred a lot sooner than first thought.
During the reionization epoch, the ominous mist of hydrogen gas that was spread throughout the young Cosmos began to clear out, and the Universe became transparent to light in ultraviolet wavelengths for the first time since it developed.
According to astronomers, this was a critical time in universal history, since it marked the first time that massive galaxies and star clusters could begin to assemble. Stars formed even during the time when the hydrogen gas was not ionized, but only in localized groups.
Until now, scientists estimated that the reionization epoch took place about 1.3 billion years after the Big Bang, or about 12.4 billion years ago. The research team says that it did not take long for reionization to complete once it started, Space
“Archaeologists can reconstruct a timeline of the past from the artifacts they find in different layers of soil. Astronomers can go one better: we can look directly into the remote past and observe the faint light from different galaxies at different stages in cosmic evolution,” Adriano Fontana explains.
“The differences between the galaxies tell us about the changing conditions in the universe over this important period, and how quickly these changes were occurring,” adds the expert, who was the leader of the new study.
He holds an appointment as a research scientist at the National Institute for Astrophysics (INAF) Rome Astronomical Observatory, in Italy. The astronomer explains that he and his team were able to push the telescope to its limits, imaging extremely distant galaxies in ultraviolet wavelengths.
Details of the research will appear in an upcoming issue of the esteemed Astrophysical Journal. The team reports that it was able to see galaxies located that developed between 780 million and 1 billion years after the Big Bang.
“The detailed analysis of the faint light from two of the most distant galaxies we found suggests that the very first generation of stars may have contributed to the energy output observed,” INAF Trieste Observatory astronomer Eros Vanzella adds in a statement.
“These would have been very young and massive stars, about 5,000 times younger and 100 times more massive than the Sun, and they may have been able to dissolve the primordial fog and make it transparent,” he concludes.