Webb reveals distant and dusty objects never seen before in a cosmic teenager

NASA's James Webb Space Telescope has revealed some never before seen objects in a galaxy cluster named "El Gordo" (Spanish for "The Fat One") in a stunning new image.

El Gordo is a cluster of hundreds of galaxies that existed when the universe was just 6.2 billion years old, making it a cosmic teen in astronomical terms. As the most massive cluster known to exist at that particular epoch, El Gordo has drawn the attention of researchers eager to delve into its mysteries. It acts as a gravitational lens, distorting and magnifying the light from distant background galaxies, providing astronomers with a unique window into the distant universe.

"Lensing by El Gordo boosts the brightness and magnifies the sizes of distant galaxies. This lensing effect provides a unique window into the distant universe," said Brenda Frye of the University of Arizona. Frye is co-lead of the PEARLS-Clusters branch of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) team and lead author of one of four papers analyzing the El Gordo observations.

Webb's infrared image of the galaxy cluster highlights several features including a bright red arc dubbed "El Anzuelo" (The Fishhook). The light from this distant galaxy took a staggering 10.6 billion years to reach Earth, and its red color results from reddening caused by dust within the galaxy itself and cosmological redshift due to its extreme distance.

By correcting the lensing distortions, the researchers determined that El Anzuelo is a disk-shaped galaxy with a diameter of about 26,000 light-years - roughly one-fourth the size of our Milky Way galaxy. Moreover, they found evidence of rapid star formation declining in the galaxy's center, a phenomenon called quenching.

Another striking feature within the image is a long, thin line called "La Flaca" (the Thin One), another lensed background galaxy whose light travelled nearly 11 billion years to reach our home planet. Nearby this galaxy lies a single red giant star, nicknamed "Quyllur" - the first individual red giant star observed beyond 1 billion light-years from Earth. Webb's infrared filters have been instrumental in making this discovery possible.

The Webb image also reveals other equally interesting objects in the galaxy cluster. The researchers identified five multiply lensed galaxies indicating a baby galaxy cluster forming approximately 12.1 billion years ago. Additionally, they identified ultra-diffuse galaxies scattered throughout El Gordo, whose stars are widely spread across space. The light from some of these distant ultra-diffuse galaxies took 7.2 billion years to reach us.

Other objects within the Webb image, while less prominent, are equally interesting scientifically. For example, Frye and her team (which includes nine students from high school to graduate students) identified five multiply lensed galaxies which appear to be a baby galaxy cluster forming about 12.1 billion years ago.

Furthermore, the team identified some of the most distant ultra-diffuse galaxies ever observed, whose light travelled 7.2 billion years to reach us.

"We examined whether the properties of these galaxies are any different than the ultra-diffuse galaxies we see in the local universe, and we do actually see some differences. In particular, they are bluer, younger, more extended, and more evenly distributed throughout the cluster. This suggests that living in the cluster environment for the past 6 billion years has had a significant effect on these galaxies," said Timothy Carleton of Arizona State University, lead author on the fourth paper.

The second and the third papers on El Gordo were led by Patrick Kamieneski of Arizona State University and Jose Diego of the Instituto de Física de Cantabria in Spain, respectively.

Youths!Webb observed galaxy cluster El Gordo, a cosmic teen that existed 6.2 billion years after the big bang. The most massive cluster of its era, it's a perfect gravitational magnifying glass, bending & distorting light from distant objects behind it: https://t.co/BrYH55h77F pic.twitter.com/JK4XFxdUQX

— NASA Webb Telescope (@NASAWebb) August 2, 2023