The James Webb Space Telescope (JWST) has captured images of barred galaxies, similar to the Milky Way, for the first time at a time when the universe was only 25% of its current age. These barred galaxies, which were not previously detected by the Hubble Space Telescope, play a significant role in galaxy evolution as they transport gas into the central region of the galaxy, boosting star formation. The finding of barred galaxies during such early epochs will require astrophysicists to revise their theories of galaxy evolution.
The JWST was able to capture these images due to its larger mirror and the fact that it can see through dust better than the Hubble, as it observes at longer infrared wavelengths. “The bars hardly visible in Hubble data just popped out in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” said Shardha Jogee, a professor of astronomy at The University of Texas at Austin. The team identified another barred galaxy, EGS-24268, also from about 11 billion years ago, which is the earliest discovery of a barred galaxy.
The discovery of barred galaxies during such early epochs shakes up galaxy evolution scenarios in several ways. “This discovery of early bars means galaxy evolution models now have a new pathway via bars to accelerate the production of new stars at early epochs,” said Jogee. The very existence of these early bars also challenges theoretical models as they need to get the galaxy physics right in order to predict the correct abundance of bars. The team will be testing different models in their next papers.
Bars play a crucial role in galaxy evolution by funneling gas into the central regions, increasing star formation. “Bars solve the supply chain problem in galaxies,” said Jogee. “A bar powerfully transports gas into the central region where the gas is rapidly converted into new stars at a rate typically 10 to 100 times faster than in the rest of the galaxy.” Bars also help to grow supermassive black holes in the centers of galaxies by channeling the gas part of the way.
The JWST, which is set to launch in October 2021, will be able to unveil structures in distant galaxies better than the Hubble due to its larger mirror and its ability to see through dust. It will also be able to observe at longer infrared wavelengths, allowing it to map the underlying structure and mass of distant galaxies with high resolution.
The JWST is a collaboration between NASA, the European Space Agency, and the Canadian Space Agency.