James Webb Telescope’s Unparalleled View of the Ghostly Light in Galaxy Clusters


SMACS-J0723.3-7327 Webb NIRCam

Image of the intracluster light of the cluster SMACS-J0723.3-7327 obtained with the NIRCAM camera on board of Webb. The data have been processed by the IAC team to improve the detection of the faint light between the galaxies (black and white). Credit: NASA, ESA, CSA, STScI

Data obtained by the new

Infrared wavelengths allow us to explore clusters of galaxies in a different way than with visible light. Thanks to its efficiency at infrared wavelengths and the sharpness of the images of the Webb, IAC researchers Mireia Montes and Ignacio Trujillo have been able to explore the intracluster light from SMACS-J0723.3-7327 with an unprecedented level of detail. In fact, the images from the Webb of the center of this cluster are twice as deep as the previous images obtained by the Webb SMACS 0723 Crop

Image of the James Webb Telescope’s “First Deep Field” that has made it possible to study the intra-cluster light of the SMACS-J0723.3-7327 cluster. Credit: NASA, ESA, CSA, STScI

“In this study, we show the great potential of Webb for observing an object which is so faint” explains Mireia Montes, the first author of the article. “This will let us study galaxy clusters which are much further away, and in much greater detail” she adds.

In order to analyze this extremely faint “ghostly” light, as well as needing the observational capability of the new space telescope, the researchers have developed new analysis techniques, which improve on existing methods. “In this work, we needed to do some extra processing to the Webb images to be able to study the intracluster light, as it is a faint and extended structure. That was key to avoid biases in our measurements“ says Mireia.

Webb Wallpaper

The James Webb Space Telescope is the next great space science observatory following Hubble, designed to answer outstanding questions about the Universe and to make breakthrough discoveries in all fields of astronomy. It is the most powerful infrared science observatory ever to be sent into space. Credit: ESA/ATG medialab

Thanks to the data obtained the researchers have been able to demonstrate the potential of the intracluster light for studying and understanding the processes which go into the formation of structures as massive as clusters of galaxies. “Analyzing this diffuse light we find 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 James Webb Telescope’s Unparalleled View of the Ghostly Light in Galaxy Clusters