A research team led by Yuchen Guo, a graduate student at the University of Texas at Austin, has announced research results showing that a spiral galaxy with a bar-shaped structure already existed in the early universe about 11 billion of years ago. The research team used observational data obtained using the James Webb Space Telescope.
【▲ Galaxy EGS-23205 about 10.7 billion years ago. Left: Hubble Space Telescope, Right: Image taken by the James Webb Space Telescope (Credit: NASA/CEERS/University of Texas at Austin)]
These two images are from the galaxy EGS-23205 about 10.7 billion years ago (redshift z = about 2.136). The image on the left shows EGS-23205 taken by the Hubble Space Telescope: although it appears to have a disk-like structure, it is unclear whether it has a rod-like structure. On the other hand, the image on the right, taken by the Webb Space Telescope, shows that it is a spiral galaxy with a bar-like structure running through the galaxy’s center and curved spiral arms.
The research team looked at hundreds of galaxies in data collected by the international research group, the Cosmic Evolution Early Release Science Survey (CEERS), using the Webb Space Telescope, to identify likely bar-like structures, and dozens of galaxies were selected visually for analysis. As a result, a total of 6 galaxies with bar-shaped structures were found that existed more than 8 billion years ago, such as the galaxy EGS-24268 (z = about 2.312) about 11 billion years ago and the aforementioned EGS -23205. One is said to have been found.
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【▲ Six galaxies from more than 8 billion years ago in which rod-like structures have been found. From the preprint of the article (Credit: Guo et al.)】
The bar structure of spiral galaxies is thought to have played an important role in the evolution of galaxies by transporting gas, which is the material for stars, to the central regions of galaxies. Professor Shardha Jogee of the University of Texas at Austin, who participated in the study, explained how the rod-shaped structure works by comparing it to a supply chain.
“Like transporting raw materials for products from ports to inland factories, rod structures strongly transport gas into the central region of the galaxy, where the gas is 10 to 100 times more potent than the rest of the galaxy. The gas is transformed into new stars at a rapid pace,” Jogee said.
Jogee points out that the discovery of rod-like structures in galaxies of the early universe means that new pathways were added to the evolutionary model of galaxies that accelerated star formation in galaxies in the first epoch. The research team will continue to analyze to correctly predict the abundance of rod structures.
Source
- Image credit: NASA/CEERS/University of Texas at Austin, Guo et al.
- UT Austin – The James Webb telescope reveals Milky Way-like galaxies in the young universe
- Guo et al. – First Look at z > 1 Bars in the Near-Infrared Rest-Frame with JWST Early CEERS Imaging (arXiv)
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