NASA’s Spitzer Space Telescope has revealed that some of the universe’s earliest galaxies are brighter than expected. The extra light is said to be a byproduct of the galaxies releasing incredibly high amounts of ionizing radiation. NASA says that the finding sheds light on the cause of the Epoch of Reionization described as a major cosmic event that turned the universe from mostly opaque to the bright and star-filled place we know today.
The new NASA study is a report on the observations of some of the first galaxies to form in the universe less than a billion years after the big bang. That means a little over 13 billion years ago. Researchers found that in a few specific wavelengths of infrared light the galaxies are considerably brighter than the scientists anticipated.
This is the first study to confirm this phenomenon over a broad sampling of galaxies from the period. This shows that the brighter than expected galaxies aren’t special cases of excessive brightness but even average galaxies present at the time were much brighter in these wavelengths than other galaxies we see today.
Evidence suggests that between 100 million and 200 million years after the big bang the universe was filled with mostly neutral hydrogen gas that might have only begun to coalesce into stars that then began to form the first galaxies. Within a billion years the universe was full of stars. The team says that electrons of the present hydrogen gas had been stripped away in a process known as ionization.
Scientists say that shorter wavelengths of light like ultraviolet, X-rays, and gamma rays were stopped from crossing the universe by colliding with neutral hydrogen that stripped the hydrogen of its electrons ionizing the gas. The question is what could have produced enough ionizing radiation to affect all hydrogen in the universe. This is what scientists want to figure out.
They note that the Spitzer space telescope with a mirror no larger than a Hula-Hoop wasn’t believed to be capable of seeing galaxies so close to the dawn of time. Scientists look forward to the launch of the James Webb Space Telescope in 2021 as it has a much larger mirror and will provide more detail for future study.