Galaxies with stellar bars from a time when the universe was only 25% as old as it is now have been seen in new images from NASA’s James Webb Telescope. Stellar bars are extended characteristics of stars that extend from the galactic centres into the outer disc.
The University of Texas at Austin claims that the discovery of such barred galaxies like our Milky Way will force astronomers to improve their theories of galactic evolution. No space telescope had ever discovered bars at such an early stage in the universe’s history before Webb took these pictures.
A JWST image of the galaxy EGS-23205 reveals a full spiral galaxy with a distinct stellar bar, in contrast to Hubble images of the galaxy which only reveal a disk-shaped smudge. The research team also discovered EGS-24268, another barred galaxy from about 11 billion years ago. These two barred galaxies are the oldest ones that have ever been found together.
By directing gas into the central region of the galaxies, these stellar bars contribute significantly to the galactic evolution by promoting star formation. They can be seen as addressing a “supply chain problem” in galaxies in some ways.
These stellar bars transport gas into the central region where it is converted into new stars at a rate that is between 10 and 100 times faster than in the rest of the galaxy, much like raw materials are transported from ports to factories to produce new products.
By guiding some of the gas part of the way, this funnelling of gases by the bars also aids in the growth of supermassive black holes in the centres of galaxies. Since early bars have been found, Jogee continued, “galaxy evolution models now have a new pathway via bars to accelerate the production of new stars at early epochs.”
These early bars present a challenge to theoretical models because they depend on accurate galaxy physics to determine the actual abundance of bars. The researchers’ next objective, according to the University of Texas at Austin, is to test various fresh models of galaxy physics.