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As astronomers look deep into space, they also see far back in time.
This galaxy formed at the dawn of the era of reionization when light first filled the Cosmos.
A long time ago, there was a galaxy far, far away… As astronomers look out further in space, they see backwards in time, nearly out to the first light in the Universe.
However, this new study refines the age of this distant object, revealing its extreme age and distance.
But measuring and verifying such a distance is not an easy task,” said Professor Nobunari Kashikawa from the Department of Astronomy at the University of Tokyo.
At extreme distances like those used in studying galaxies, astronomers often speak in terms of the redshift of a target, denoted with the letter z.
This new study reveals GN-z11 has a redshift value around z=11, the highest shift (and therefore, the greatest distance) ever seen.
It’s not polite to ask a galaxy its age… The red shift of spectral lines from GN-z11 (top) reveal the great age, and magnificent distance from us, of GN-z11.
Chemical signatures can be seen in the spectra of an object, revealing the composition of a distant target.
When light from distant bodies is broken up into its component colors, these emission lines shift to the red end of the spectrum.
The most distant an object is from us, the faster it is seen to be receding, producing a greater red shift.
Therefore, by measuring the red shift of a target galaxies, astronomers are able to calculate its distance from Earth.
“We looked at ultraviolet light specifically, as that is the area of the electromagnetic spectrum we expected to find the redshifted chemical signatures.
So we turned to a more up-to-date ground-based spectrograph, an instrument to measure emission lines, called MOSFIRE, which is mounted to the Keck I telescope in Hawaii.
The MOSFIRE instrument at Keck I allowed astronomers to carefully measure the distance to the most-distant galaxy ever seen.
Image credit: Keck Observatory MOSFIRE was able to determine the red shift of emission lines from GN-z11 at a detail 100 times greater than ever before.
If future observations confirm the distance found in this study, than GN-z11 is the most distant galaxy ever seen in the Cosmos.
Researchers also found an unexpected sight while studying GN-z11 — a bright flash of ultraviolet light from the distant galaxy.
Known objects that give rise to such transients include gamma-ray bursts (GRBs), the most luminous explosions in the Universe… These high-redshift GRBs and their associated emission can be used to probe the star formation and reionization history in the era of cosmic dawn,” researchers describe in Nature Astronomy.
Future instruments and observations, including the James Webb Space Telescope, could reveal the progenitors of galaxies like GN-z11, emitting some of the oldest light in the Universe.
Tune in every Tuesday for updates on the latest astronomy news, and interviews with astronomers and other researchers working to uncover the nature of the Universe.