Scientists from the California Institute of Technology (Caltech) have detected the presence of the universe’s farthest galaxy, which is about 13.2 billion years old, meaning it is the oldest and most distant galaxy ever found. To put the discovery into context, the universe itself is about 13.8 billion years old.
According to Geek, the light from the galaxy must have been emitted when the universe was still very young, and scientists suspect its luminosity could be powered by unusually hot stars. Data from the Hubble Space Telescope and Spitzer Space Telescope were used to identify the galaxy, which has been termed EGS8p7 by the Caltech scientists, based on the alphanumeric nomenclature system scientists use to name distant space objects.
Remarkably, the group of scientists who were studying the universe’s farthest objects were not expecting to detect any light emanating from EGS8p7, and as a result, the discovery has left them pleasantly surprised. Sirio Belli, one of the scientists working on the project, said that the galaxy must have special properties for the emitted light to have been observed now.
“It may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times.”
In theory, it should not have been possible for the Caltech scientists to observe light emerging from the detected galaxy. In its first billion years after formation, the universe was a soup of charged particles and light packets (photons). When the first galaxies emerged, a process of reionization of the universe’s neutral gases took place and the universe remains ionized even today.
However, before the reinoization took place, clouds of neutral hydrogen atoms would have absorbed certain radiation emitted by young, newly forming galaxies — including the so-called Lyman-alpha line, the spectral signature of hot hydrogen gas that has been heated by ultraviolet emission from new stars, and also the most commonly used indicator of star formation.
This absorption would have prevented the scientists from observing the Lyman-alpha line from the detected galaxy. The scientists reckon the discovery could bring about a whole revolution in the way we think about the evolution of the universe in its first few billion years. NASA Hubble post-doctoral scholar in astronomy Adi Zitrin admitted as much.
“Reionisation is one of the major key questions to answer in our understanding of the evolution of the universe.”
Another scientist, Richard Ellis, commented that the discovery was wildly fascinating for the very reason that it raises questions about our current understanding of how the universe evolved after the Big Bang.
“The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy, corresponding to a time when the universe should be full of absorbing hydrogen clouds.”
After the latest discovery, EGS8p7 becomes the farthest galaxy known to man. The study was published in the journal Astrophysical Journal Letters.
[Photo via NASA]