The University of Tokyo recently announced that astronomers have discovered the most distant and oldest known galaxy. The galaxy numbered GN-z11 may have a rather common name, but it is supposed to be the most distant and oldest galaxy known to have been observed.
A research team led by Professor Nobunari Kashiwawa of the University of Tokyo is on a research mission to find the most distant observable galaxies in the universe in order to understand how and when they formed.
“Based on previous studies, galaxy GN-z11 appears to be the farthest galaxy from us, at 13.4 billion light-years, or 13.4 non-billion kilometers, from Earth (13.4 non-billion is 134 followed by 30 zeros).” Professor Kashiwawa said in a statement released by the University of Tokyo, “But measuring and verifying such a distance is not an easy task.”
To determine the distance between GN-z11 and our Earth, Professor Kashiwawa’s team studied the redshift of galaxies. Typically, the farther a cosmic object is from us, the greater its redshift.
In addition, the team studied the emission spectral lines of GN-z11, the chemical signal observable in the light emitted by cosmic objects.
By scrutinizing this information, the team was able to figure out how far the light emitted from GN-z11 must travel to reach us, providing them with a tool to estimate its distance from Earth.
“We looked specifically at the ultraviolet because this is the region of the electromagnetic spectrum where we expect to find red-shifted chemical signatures.” Professor Kashiwawa said, “The Hubble Space Telescope detected this information several times in the GN-z11 spectrum.”
“But,” he added, “even the Hubble telescope could not resolve the ultraviolet emission spectra we needed. Therefore, we turned to a newer generation of ground-based spectrometers. It’s an instrument for measuring emission spectral lines called MOSFIRE, which is mounted at the Keck Observatory in Hawaii.”
Using MOSFIRE, the team was able to observe and study the emission spectral lines from galaxies in detail. If other observations confirm this new finding, GN-z11 will officially become the most distant galaxy known.
The new study was published in the journal Nature Astronomy on December 14, 2020.
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