James Webb Space Telescope: Earliest galaxies are a mystery to researchers

Shortly after its commissioning, the James Webb Space Telescope found “extraordinarily bright” galaxies from the early days of the Universe that have baffled the research community. The Space Telescope Institute, which is responsible for the scientific work of the instrument, now reports this on the basis of two verified research documents.

The brightness and shape of the galaxies in their state 350 and 450 million years after the Big Bang, respectively, indicate that the first stars formed as early as 100 million years after the Big Bang, the research team writes. The “dark ages” would then have been much shorter than assumed.

The James Webb Space Telescope was known to discover a large number of particularly distant galaxies immediately after it started work. There were also doubts about the alleged finds, but the discoveries now presented have survived their peer review. These are objects designated GLASS-z12 and GLASS-z10, ie galaxies with redshifts of z = 12.5 and z = 10.5. The former is thus the most distant known galaxy we have found so far. The distances have yet to be confirmed. Both would turn gas into stars extremely quickly, the research team explains. They are spherical or disc-shaped and are only a few percent the size of our Milky Way.

The “silent, orderly disks” of the galaxies found would challenge our understanding of how the first galaxies formed in the “crowded, chaotic early universe,” says Erica Nelson, who was involved in the study. In addition, based on all calculations, it was also assumed that the search for such early galaxies would take much longer. Many relatively bright stars could be responsible for the unexpectedly high brightness. But it is also possible that there are many very bright stars of the so-called Population III, the very first generation of stars in the first place. They have never been directly observed before. Initial data would indicate this, but only more detailed analyzes could prove it.

The information about the distance between the two galaxies was still based on a measurement of the infrared radiation. For independent confirmation, spectra would need to be determined and the actual redshift measured, the team writes. On its way to us, the expansion of space shifts the light itself to the red and finally to the infrared, which is why the value is also a measure of the age of a cosmic object. Nevertheless, the finds are already fascinating and a whole new chapter in astronomy begins, says astronomer Paola Santini: “It’s like an archaeological dig where suddenly you find a lost city or something unknown. It’s just breathtaking.” The compact and extremely bright galaxies are completely different from the Milky Way and its neighbors, adds research leader Tommaso Treu.

The James Webb Space Telescope is operated by the space agencies NASA, ESA and CSA and was launched on December 25, 2021. After a complex self-expansion procedure, it arrived at the L2 Lagrange point a month later. Here it faces away from the sun, earth and moon into space so that their heat radiation does not interfere with the infrared telescope. A huge protective screen blocks them.

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Since the scientific work started in early July, the quality of the data has fascinated not only the research community. The first recordings are currently being published immediately. The goal is for the scientific community to learn how to make the best use of the new observatory and its instruments. The study of the two extremely early galaxies is now presented in The Astrophysical Journal.


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