An article accepted for publication in “The Astrophysical Journal Letters” reports the discovery of six barred spiral galaxies that are between 8.4 and 11 billion years old. A team of researchers used the James Webb Space Telescope within the CEERS survey to observe enough details of these galaxies to identify the two extensions of stars that start from their center and reach the outer disk in a structure that resembles a bar. It’s a crucial structure for the evolution of these galaxies, as it favors the growth of the supermassive black holes at their center and star formation in their central regions.
Spiral galaxies are the most common type in the universe, and most of them have a structure with a bar-like shape, including the Milky Way. Other types of galaxies can also have that type of structure, so sometimes, the generic expression barred galaxies is used. The processes leading to the formation of the bar are not yet clear but it could be a consequence of a tidal force between galaxies.
Studies of the formation and evolution of galaxies are always important in astronomy. The start of the James Webb Space Telescope’s science mission offers new hope for better understanding the processes that occur over the life of a galaxy. The Cosmic Evolution Early Release Science Survey (CEERS) is among the ones already investigating primordial galaxies and is already offering interesting results confirming the extraordinary level of its performance.
In a sample of 348 ancient galaxies, the James Webb Space Telescope identified six barred spiral galaxies, shown in the top image (Courtesy NASA/CEERS/University of Texas at Austin). The galaxy cataloged as EGS-23205 has an estimated age of about 10.7 billion years and was already studied with the Hubble Space Telescope but without being able to obtain enough detail to resolve the central bar: the bottom image (Courtesy NASA/CEERS/University of Texas at Austin) shows EGS-23205 as seen by Hubble on the left and Webb on the right.
The bar’s role is crucial in the evolution of a galaxy because it carries gas. That gas can feed the supermassive black hole at the center of the galaxy and can form new stars at a rate 10 to 1,000 times faster than in the rest of the galaxy. In short, this is useful information for various studies related to the evolution of galaxies.
This study confirms that barred galaxies are common and above all shows that they had already formed when the universe was young. This is important for testing current models of galaxy formation and evolution. For this reason, the article reporting the discovery of the six barred galaxies is only the first in a series in which various models will be tested.
The identification of ancient barred galaxies represents another confirmation of the extraordinary performance of the James Webb Space Telescope. In a few months, it’s showing that it can offer much better observations of ancient galaxies than other telescopes that are useful to make a leap forward in astronomical research.
