Space science media Space.com reported on the 21st (local time) that the James Webb Space Telescope has discovered candidates for the oldest galaxies in the history of space observations just a week after the first observation photos were released.
Researchers at the University of Geneva in Switzerland and the Harvard-Smithsonian Institute for Astrophysics in the United States published the results of their research on the arXiv, a site for pre-publication of the thesis on the 20th.
The researchers explained that they discovered galaxies GLASS-z13 and GLASS-z11 about 13.5 billion years ago with the James Webb Space Telescope. The oldest galaxy observed in previous observations is GNz11, discovered by the Hubble Space Telescope in 2015, which is 13.4 billion years old.
To determine the age of the galaxies, the researchers used the phenomenon of ‘redshift’, in which the wavelength of light becomes longer and appears red. As the universe expands, the wavelength of light passing through the expanding space also increases. At this time, visible light also becomes infrared with a longer wavelength, and light coming from a distant celestial body tends to have a larger redshift.
The galaxy’s redshift was measured by James Webb’s Near Infrared Camera (NIRCam). The researchers will then analyze the spectrum of light emitted by the galaxy and further measure how redshifted the light emitted by certain atoms and molecules is. After this work, the ages of these galaxies will be finalized.
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GLASS-z13 is said to be 1600 light years in diameter, and GLASS z-11 is known to be 2300 light years in diameter. In particular, it was confirmed that GLASS-z11 had already formed a spiral disk structure, so stars were formed earlier than expected in early galaxies.
In addition, the two galaxies may have developed into giant elliptical galaxies of their present size by merging with other galaxies, the researchers explained.