A team of researchers revealed on Friday that they have found the farthest galaxy ever discovered to date. The galaxy dubbed EGS8p7 formed shortly after the birth of the universe, which occured about 13.8 billion years ago.
Study researcher Sirio Belli, a Caltech graduate student, described the newly found galaxy as luminous that may be powered by remarkably hot stars. He added that the galaxy may have special properties that allowed it to produce a large bubble of ionized hydrogen earlier than possible for the most galaxies at the time.
Astronomers were able to observe a Lyman-alpha line, the spectral signature of hot hydrogen gas heated by ultraviolet emission coming from new stars. Radiation of this kind should have been consumed and absorbed by clouds of neutral hydrogen atoms in the early universe.
"We report the discovery of Lyman-alpha emission (Lyα) in the bright galaxy EGSY-2008532660 (hereafter EGSY8p7) using the Multi-Object Spectrometer For Infra-Red Exploration spectrograph at the Keck Observatory," the researchers reported. "GSY8p7 is the most distant spectroscopically confirmed galaxy to date."
The universe was a primordial soup of charged particles and light right after the Big Bang. Free electrons made it impossible for the photons to travel through space so the light could not be transmitted in the early universe. The universe eventually cooled enough to allow free electrons and protons to merge and form into neutral hydrogen atoms to allow light to travel.
Between 500,000 to a billion years after the universe was formed, the early galaxies reionized the neutral gas. The universe remained ionized until today. Before reinonization though, the neutral hydrogen atoms would have absorbed radiations that include the Lyman-alpha line emitted by young galaxies.
"The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the universe should be full of absorbing hydrogen clouds," said Richard Ellis, from the University College, London.
The researchers said that the findings suggest that ionization did not occur uniformly. It is possible that the newly discovered galaxy has such large and hot stars it was able to ionize its own clouds of hydrogen gas enabling radiation to escape much earlier than its counterparts.
The findings were published in the The Astrophysical Journal Letters on Aug. 28.
