There is nothing larger than a galaxy cluster in the known universe, but how galaxy clusters form remains largely a mystery to scientists. The surest way to understand this process is to find clusters, or primordial cluster embryos, in the early universe. One of these early geological formations was discovered by the James Webb Space Telescope.

Using the Webb NIRCam camera to create detailed images of the starry sky in the Grotto Strip area, we were able to discover a chain of 20 huge and widespread galaxies there. The structure resembles a curved arc spanning 13 million light-years long and approximately 650,000 light-years wide. For comparison, our Milky Way is about 100,000 light years wide. This formation was named “Space Vine” because of its appearance. All galaxies in Vine are about the same distance from us, with a redshift value of about 3.44. That means it took between 11 and 12 billion years for their light to reach us, most of the universe’s estimated 13.8 billion year lifetime. Scientists measured the mass of this primordial galaxy cluster to be 1010.9 suns, making it the most massive galaxy cluster embryo ever discovered in the early universe. Currently, the mass of “Rosa” could reach 1014 solar masses.

The two largest galaxies in the cluster (labeled A and E in the image) are identified as quiet. This means that their star formation process has completed or is nearing completion. This is surprising for a galaxy at such an early stage, and scientists have not yet been able to provide a clear explanation for it. For one, both galaxies may have experienced mergers with other galaxies, which led to increased star formation activity and accelerated material consumption. Afterwards, this pair of galaxies most likely became the center of a giant galaxy cluster, but where they are now is a mystery. Due to the expansion of the universe, he is lost in the depths of space, but we will never know about it.

source: https://arxiv.org/abs/2311.04867