The first deep field image of the universe taken by the James Webb Space Telescope (JWST) allowed scientists to study the faint, ghostlike light from intergalactic orphan stars in galaxy clusters.
These stars are not gravitationally bound to the galaxies, they are pulled away from their homes and drifted into intergalactic space by the enormous tidal forces generated between galaxies in clusters. The light from these stellar orphans is called intracluster light and is so faint that it has only one percent of the brightness of the darkest sky to be seen a land.
Not only could studying this ghostly light from orphan stars reveal how galaxy clusters form, it could give scientists hints about the properties of dark matterthe mysterious substance that accounts for about 85% of the mass of the universe.
Dark matter doesn’t interact with light, which means scientists know it’s not like the everyday matter it’s made of protons And the neutrons. Its existence can currently only be inferred from its gravitational interactions, which literally prevent the stars and planets of galaxies from flying away.
The JWST sees the universe in infrared light, the frequencies of electromagnetic radiation that allow astronomers to see galaxy clusters differently than pictured in visible light.
The sharpness of JWST’s infrared images allowed Instituto Astronomy Institute of the Canary Islands (IAC) researchers Mireia Montes and Ignacio Trujillo to study the light within galaxy cluster SMACS-J0723.3-7327 at an unprecedented level of detail.
This sharpness stems from the fact that JWST images of SMACS-J0723.3-7327, located about 4 billion light-years from Earth in the constellation Phulan, are twice as deep as observations of the same group previously taken by Hubble Space Telescope.
said first research author Montes V statement (Opens in a new tab). “This will allow us to study galaxy clusters that are much more distant, and in much greater detail.”
Studying this faint light inside the cluster requires more than just the observational power of JWST, which means the team also needs to develop new image analysis techniques. “In this work, we needed to do some additional processing of the JWST images to be able to study the light inside the cluster, as it is a faint, elongated structure,” Montes explained in the release. “This was key to avoid bias in our measurements.”
The data obtained by scientists is a striking evidence of the potential of light within a cluster to reveal the processes behind the formation of structure in galaxy clusters.
“When analyzing this scattered light, we found that the inner parts of the cluster are formed by the merger of massive galaxies, while the outer parts are caused by the accumulation of galaxies similar to our own.” Milky WayMontes said.
In addition, because the stars within the cluster follow the gravitational influence of the cluster as a whole rather than that of individual galaxies, the light from these stellar orphans presents an excellent way to study the distribution of dark matter in these clusters.
“The JWST test will allow us to characterize the distribution of dark matter in these massive structures with unprecedented precision, and shed light on their fundamental nature,” added Trujillo, second author of the study.
The duo’s research was published Dec. 1 in Astrophysical Journal Letters (Opens in a new tab).
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