The first deep-field image of the cosmos captured by the James Webb Space Telescope (JWST) has allowed scientists to study the faint, almost ghostly light from orphan stars that exist between galaxies in galaxy clusters.
These stars, which are not gravitationally bound to galaxies, are being pulled from their homes and drifting into intergalactic space by the massive tidal forces generated between galaxies in clusters. The light from these orphan stars is called intracluster light, and is so faint that it’s only one percent the brightness of the darkest sky you can see across Earth.
Studying this eerie light from orphan stars could not only show how galaxy clusters form, but could also give scientists clues about the properties of Dark matterthe mysterious substance that makes up about 85% of the mass of the universe.
Dark matter doesn’t interact with light, which means scientists know it’s not the same as everyday matter that makes it up protons and neutrons. Its presence can currently only be inferred from its gravitational interactions, which literally prevent stars and planets from galaxies from flying apart.
The JWST sees the universe in infrared light, frequencies of electromagnetic radiation that allow astronomers to see galaxy clusters differently than in visible light.
The sharpness of the JWST infrared images allowed Instituto de Astrofísica de Canarias (IAC) researchers Mireia Montes and Ignacio Trujillo to study the intracluster light of galaxy cluster SMACS-J0723.3-7327 in an unprecedented level of detail.
This sharpness comes from the fact that JWST images of SMACS-J0723.3-7327, located about 4 billion light-years from Earth in the constellation of Volans, are twice as deep as observations of the same cluster previously made by the became Hubble Space Telescope.
“In this study, we show the great potential of JWST for observing such a faint object,” said the research’s first author, Montes, in a expression (opens in new tab). “This allows us to study much more distant galaxy clusters and in much more detail.”
However, studying this faint intracluster light required more than the JWST’s mere observational power, meaning the team also had to develop new image analysis techniques. “In this work, we had to do additional processing on the JWST images to study the intracluster light because it is a faint and extended structure,” Montes explained in the statement. “That was the key to avoiding distortions in our measurements.”
The data obtained by the scientists is an impressive demonstration of the potential of intracluster light to reveal the processes behind structure formation in galaxy clusters.
“In analyzing this diffuse light, we find that the inner parts of the cluster are formed by a merger of massive galaxies, while the outer parts are due to the accretion of galaxies similar to ours Milky WayMontes said.
In addition, since the stars within the cluster follow the gravitational influence of the cluster as a whole and not that of individual galaxies, the light from these orphan stars provides an excellent opportunity to study the distribution of dark matter in these clusters.
“The JWST will allow us to characterize the distribution of dark matter in these enormous structures with unprecedented precision and shed light on their fundamental nature,” added study second author Trujillo.
The duo’s research was announced on 12. 1 im Astrophysical Journal Letters (opens in new tab).