Astronomers have discovered one of the youngest galaxies in the distant universe. Containing stars that formed 13.5 billion years ago, merely 200 million years after the Big Bang, the finding addresses questions regarding the origins of the first galaxies and how the early universe evolved.
NASA’s Hubble Space Telescope was the first to spot the new galaxy. Detailed observations of light from the galaxy recorded by the W. M. Keck Observatory in Mauna Kea, Hawaii revealed the light from the galaxy dates back to when the universe was only 950 million years old. The universe formed about 13.7 billion years ago.
Infrared data from the Hubble Space Telescope and NASA’s Spitzer Space Telescope revealed that the galaxy’s stars are quite old, having formed when the universe was at the very young age of 200 million years.
Johan Richard of the Center for Astronomical Research, Observatory of Lyon, France, lead author of a new study accepted for publication in the Monthly Notices of the Royal Astronomical Society, believes that the finding challenges theories regarding when galaxies formed in the first years of the universe, and that it could even help solve the mystery of how the hydrogen fog that filled up the early universe was cleared.
This is not the most distant galaxy ever observed, but it is one of the youngest to be observed so clearly. Normally, such galaxies are very faint and therefore difficult to study. In this case, however, the galaxy’s image is being naturally magnified.
The presence of a massive cluster of galaxies, Abell 383, located in front of it, makes it appear 11 times brighter than it would without this phenomenon, and is known as the “gravitational lensing” effect.
“Without this big lens in space, we could not study galaxies this faint with currently available observing facilities,” co-author of the study, Eiichi Egami of the University of Arizona in Tucson, said. “Thanks to nature, we have this great opportunity to see our universe as it was eons ago.”
The findings could help explain how the early universe became “reionized.” At some point in its early history, our universe transitioned from the so-called dark ages to a period of light as the first galaxies and stars began to form.
The light from the stars ionized neutral hydrogen atoms floating through space, leaving them with a charge. Ultraviolet light could now travel through what had previously been an obscuring fog.
The discovery of a galaxy possessing stars that formed only 200 million years after the Big Bang helps astronomers constrain this period of cosmic reionization.
When the galaxy in question was developing, its hot, young stars would have ionized significant amounts of the neutral hydrogen atoms in space. A population of similar galaxies is likely to have contributed to this reionization, but they are too faint to see or study since they do not all experience the magnifying effects of gravitational lensing.
NASA’s James Webb Space Telescope (JWST), scheduled to launch later in the decade, will be able to see the faint galaxies without the gravitational lensing effect.
The JWST is a successor to Hubble and Spitzer, and will see infrared light from the missing group of early galaxies. The mission is expected to deliver some of the universe’s greatest secrets.
“Seeing a galaxy as it appeared near the beginning of the universe is an awe-inspiring feat enabled by innovative technology and the fortuitous effect of gravitational lensing,” Jon Morse, Astrophysics Division director at NASA’s headquarters in Washington, D.C., said. “Observations like this open a window across space and time, but more importantly, they inspire future work to one day peer at the stars that lit up the universe following the Big Bang.”
Please note All comments are eligible for publication in The News-Letter.