NASA’s James Webb Space Telescope has discovered two of the oldest galaxies. It is known that one of them was formed 350 million years after the Big Bang, and the other – 450 million years later.
According to the current ideas of cosmologists, the first galaxies appeared in the Universe approximately 300-400 million years after the Big Bang, when its matter had time to cool down to temperatures at which cold clouds of gas can form, inside which stars arise. Scientists have been looking for and studying the properties of such galaxies for several decades in the hope of revealing their role in the chemical evolution of the universe.
The researchers used images taken by “James Webb” to search for analogues of the galaxy GN-z11, one of the most distant objects in the early universe. Its properties were studied with the help of Hubble and other space and ground-based observatories. To detect ancient galaxies, scientists took advantage of the characteristic features of the spectrum of such objects, which reflect the interaction of the radiation of their young and bright stars with the surrounding accumulations of dust and gas.
As it turned out, in the first pictures of “James Webb” there are two such objects at once: GLASS-z12 and GLASS-z10. The first of them is 13.4 billion light-years from Earth, and the second is 13.3 billion light-years away, which makes them the same age as GN-z11. In shape and size, both of these galaxies turned out to be very similar to GN-z11 and other ancient star clusters, but at the same time their brightness turned out to be much higher than expected.
Follow-up observations of GLASS-z12 and GLASS-z10 and the study of the resulting spectra of these galaxies, as astronomers hope, will help them uncover the reason for the anomalously high brightness of these objects, as well as understand which stars were present inside them. This information is critical to understanding how the universe became transparent to electromagnetic waves and how it became saturated with heavy elements.