In 2012, scientists discovered an exceptionally large cluster about seven billion light-years from Earth. James Webb visited this group, which led to this beautiful photo.
The block is called ACT-CL-J0102-4915 and has been dubbed “El Gordo”. This is the Spanish word for “great person”. The cluster consists of hundreds of galaxies. In addition, El Gordo is composed of warm gas and dark matter.
We see the block as it appeared at a very young age. “Compared to any known cluster at this distance, this cluster is the largest, hottest, and also produces the most X-rays,” researcher Felipe Mignanto said in 2014. A surprising discovery, because according to cosmological models there would be a chance of finding such clusters very early in the universe.
The researchers had hoped to image El Gordo again using Hubble. This dream has now come true in one form or another. Not Hubble, but James Webb aimed his mirrors at the cluster.
In this week’s satellite image, we see countless galaxies. El Gordo works like a gravitational lens. The galaxies in this cluster have a very strong gravitational field. Light from objects behind the cluster is deflected. This has all kinds of consequences. For example, the image of a galaxy can be distorted or stretched. Sometimes it even produces several images, for example in the case of an Einstein cross.
Also in El Gordo’s case, we see gravitational lensing at work. The Thin Bar (A) and the Red Fish Hook (B) are distorted background galaxies.