In the GN-z11 era, galaxies were made of stronger things and just don’t understand young whips like the Milky Way. Such is the life of older galaxies. In this case, the oldest we know of. In fact, it is so far away that it defines the very boundary of the observed universe itself.
Professor Nobunari Kashikawa of the Department of Astronomy at the University of Tokyo searched for the most distant galaxy he could observe to find out how and when it formed. In their search, he and his team were able to more accurately find the distance to an aging galaxy.
Although it has been known for some time that GN-z11 is the oldest known galaxy, measuring the distance to it has proven to be a real challenge.
“From previous studies, the GN-z11 galaxy appears to be the furthest we can detect, with 13.4 billion light-years or 134 non-million kilometers (that’s 134 followed by 30 zeros),” Kashikawa said. “But measuring and checking such a distance is not an easy task.”
To measure distance, Kashikawa measured the redshift or how much light shifted toward the red end of the spectrum as galaxies drifted apart by universal expansion. The farther the galaxy is, the higher the redshift. Using the Keck I telescope, astronomers were able to get a decent repair on the GN-z11.
“We concentrated on ultraviolet light because that’s the area of the electromagnetic spectrum that we expected to find a red-shifted chemical signature,” Kashikawa said. “The Hubble Space Telescope has discovered the signature several times in the GN-z11 spectrum. However, not even Hubble can solve the lines of ultraviolet radiation to the extent we should. Therefore, we turned to a more modern terrestrial spectrograph, an instrument for measuring emission lines, called MOSFIRE. “
When working with distances on these huge scales, it just doesn’t make sense to use our familiar units of kilometers and miles, or even multiples. Instead, astronomers use a value known as the redshift number denoted by z.
Using MOSFIRE (a multi-object spectrometer for infrared research), the team recorded emission lines with GN-z11 in detail, which allowed them to make a far better estimate of its distance than was possible from previous data, confirming the galaxy’s ‘farthest’ status.
The study was published in the journal Nature Astronomy on December 14.