According to the Purple Mountain Observatory of the Chinese Academy of Sciences on the 5th, an international team led by researchers from the Observatory discovered a pair of massive serene galaxies that may be merging in the dense region of the core of the original galaxy cluster, revealing that the brightest cluster of galaxies was formed before the original galaxy cluster relaxed. This provides important observational constraints for understanding the formation of the brightest cluster galaxies with high redshifts and the termination mechanism of star formation in massive galaxies.
Galaxy clusters are the densest systems in the macrostructure of the universe, inhabited by a class of supermassive elliptical galaxies known as the brightest clusters. Due to their extreme formation conditions, these galaxies are also often used to test theoretical models for the formation of massive galaxies, galaxy clusters, and large-scale structures. However, the mechanism of its formation is still a mystery to be solved.
At present, the observation of the brightest clusters of galaxies is limited to geologically forced, and it is unclear whether the growth of such galaxies is crucial for the formation of mature galaxy clusters. Therefore, direct observation of the brightest cluster galaxies in the early universe protocluster is of great significance for understanding the relationship between the brightest cluster galaxies and their host clusters, as well as their formation and evolution. Dong Dong, a postdoctoral fellow at the Purple Mountain Observatory of the Chinese Academy of Sciences, said.
Using the near-infrared seamless spectroscopy and series of observations from the International Space Hubble Telescope, researchers have discovered a pair of large-mass serene galaxies that may be merging, which are elliptical in shape, have obvious absorption characteristics such as Balmer, and inhabit the densest region of the core of the original galaxy cluster. Based on cosmological model estimates, the researchers found that even if the two galaxies eventually merged to form a larger-mass mature brightest cluster galaxy, it still occurred before the original galaxy cluster was forced.
Interestingly, for the first time, the research team also found that the star-forming activity of the proto-galaxy cluster shows a significant gradient distribution from its compact core to its periphery, that is, the densest core region is the quiet galaxy, the medium-density region is the normal star-forming galaxy, and the low-density peripheral region is the submillimeter-wave galaxy with intense star-forming activity.
The research results were published in the international astrophysical journal "The Astrophysical Journal".
*: China News Network.