The James Webb reveals galaxies similar to the Milky Way in the early universe

Images of the galaxy EGS23205. On the left the one taken by the Hubble telescope and on the right that of the James Webb telescope, in which it can be seen that it is a spiral galaxy with a clear stellar bar. EFE/NASA/CEERS/University of Texas at Austin.

The James Webb Space Telescope has revealed the existence of two “barred” galaxies, similar to the Milky Way, at a time when the universe was just 25% of its current age, forcing astrophysicists to refine their theories on the evolution of galaxies. A study led by the University of Austin in Texas (USA) and which has been accepted for publication in The Astrophysical Journal Letters speaks of the existence of these two barred galaxies, which have a bar-shaped stellar structure that extends from side to side from the center to its outer discs. Barred galaxies had never been detected in such an early phase of the universe before the James Webb came into operation, which “will force astrophysicists to refine their theories about the evolution of galaxies,” says the university.

One of these galaxies, EGS-23205, had already been observed by the Hubble Space Telescope, predecessor of the Webb, but the image it gave was little more than a disk-shaped blob. However, the new telescope, launched in December 2021, is much more powerful, allowing it to observe the underlying structure of galaxies, thus offering a clear image of the spiral galaxy with a stellar bar. The team identified another barred galaxy, EGS-24268, also from around 11 billion years ago, making two such bodies farther back in time than any previously discovered. The article also includes samples from four other barred galaxies from more than 8 billion years ago.

The bars play an important role in the evolution of galaxies by funneling gas into the central regions, driving star formation. One of the signatories to the article, Shardha Jogee, said that these bars “solve the supply chain problem” in galaxies.” “Just like we need to get raw materials from the port to inland factories that make new products, a rod powerfully transports gas to the Midwest, where it quickly turns into new stars at a rate typically 10 to 100 times faster. than in the rest of the galaxy,” he explained.

These structures also contribute to the growth of supermassive black holes at the centers of galaxies by funneling gas part of the way. The discovery of bars in early epochs means, according to Jogee, that models of galaxy evolution “now have a new way, through bars, to accelerate the production of new stars in early epochs.”