The James Webb telescope keeps giving us unique and never-before-seen images of the vast and sublime Universe.
This new journey through space has only been going on for a few months, but the James Webb Telescope has captured ghostly light in detail for the first time. From its first photographs to the most recent discoveries, Webb’s gaze is arguably the most exceptional yet created by humans. Einstein rings, cosmic tarantulas, and colliding galaxies, the Universe is different for us since this telescope has been in deep space.
As if those infinite captures were not enough, James Webb captured ghostly light for the first time. It was all discovered in what astronomers call intracluster light, that is, in the light that lies between galaxies. But some of you are probably wondering...
What are galaxy clusters or intracluster?
In essence, a galaxy cluster is a set of more than several tens of concentrations of galaxies, literally. Due to gravity and proximity between some of these objects, clusters are formed, for example, the galaxy in which we live is located within a cluster better known as the Local Group.
However, within the clusters are not all galaxies in perfect composition, there are also remains of galaxies. When a part of the stars wandering in the intergalactic space has been torn away by the enormous tidal forces generated between the different galaxies of the cluster, they are called intracluster light.
Those remnants of star or galaxy brightness - which are too faint - usually comprise only 1% or less of the brightness of the darkest sky that can be observed from Earth. But Webb’s ability to look at the infrared universe is definitely better than that of any human being on the planet.
The telescope can gather information farther from the center of a galaxy cluster than was possible using optical telescopes, as had been attempted until now. But placed in orbit at Lagrangian point 2, it is easy for Webb to reveal the ghost light.
Where did James Webb capture ghost light?
Astronomers at the Instituto de Astrofísica de Canarias, Mireia Montes, and Ignacio Trujillo, have been able to explore the intracluster light of a particular cluster of galaxies in unprecedented detail. This is the cluster called SMACS-J0723.3-7327, which is only 4,000 million light-years away from Earth and is located in the sky visible from the Southern Hemisphere of the Earth in the direction of the constellation of Volans.
Analysis of this diffuse light allowed astronomers to discover that the inner parts of the cluster are being formed by a merger of massive galaxies, while the outer parts are due to the accretion of galaxies similar to our own Milky Way.
Thanks to James Webb’s capture of the ghost light from the center of this cluster, they are twice as deep as those previously taken by the Hubble Space Telescope, which will allow them to study galaxy clusters farther away and in much greater detail. The researchers had to develop new analysis techniques to be able to analyze this extremely faint ghost light, which will provide new insights into the formation processes of galaxy clusters and the properties of dark matter.
“In this study, we demonstrate the great potential of Webb to be able to observe something so faint. This will allow us to study galaxy clusters farther away and in much greater detail.”
The stars emitting the intracluster light follow the gravitational field of the cluster, which allows us to track the distribution of dark matter, allowing us to accurately characterize the distribution of dark matter in these giant structures.
Story originally published in Spanish in Ecoosfera