The first deep-field image of the cosmos taken 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 galactic clusters.
These stars are not gravitationally bound to galaxies, but are pulled from their homes and drifted into intergalactic space by the enormous tidal forces generated between galaxies in clusters. The light emitted by these stellar orphans is called intracluster light and is so faint that it is only one percent of the brightness of the darkest sky seen above Earth.
Studying this ghostly light from orphan stars could not only reveal how galactic clusters form, but it could also give scientists hints about the properties of dark matter, the mysterious substance that makes up about 85% of the universe’s mass.
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Dark matter doesn’t interact with light, which means scientists know it’s not the same as everyday matter made up of protons and neutrons. Its presence can currently only be inferred from its gravitational interactions that literally prevent the stars and planets of galaxies from flying apart.
The JWST sees the universe in infrared light, frequencies of electromagnetic radiation that allow astronomers to see galactic clusters differently than the picture painted in visible light.
The sharpness of the JWST infrared images allowed researchers Mireia Montes and Ignacio Trujillo of the Instituto de Astrofísica de Canarias (IAC) to study the intracluster light of the galactic cluster SMACS-J0723.3–7327 with an unprecedented level of detail.
Image of the James Webb telescope’s “First Deep Field” that has allowed the study of the intra-cluster light from the SMACS-J0723.3-7327 (Image credit: NASA, ESA, CSA and STScI)
This sharpness comes from the fact that JWST images of SMACS-J0723.3–7327, which is located about 4 billion light-years from Earth in the constellation Volans, are twice as deep as observations of the same cluster previously taken by Hubble. are made. Space Telescope.
“In this study, we show the great potential of JWST for observing an object that is so faint,” said the study’s first author, Montes, in a statement.
pronunciation (opens in new tab). “This allows us to study clusters of galaxies that are much further away, and in much greater detail.”
However, studying this faint intracluster light required more than just the observational power of the JWST, which meant the team also had to develop new image analysis techniques. “In this work, we had to do some additional processing on the JWST images in order to study the intracluster light, as it is a faint and extensive structure,” Montes explained in the statement. “That was key to avoid bias in our measurements.”
The data the scientists obtained is a striking demonstration of intracluster light’s potential to reveal the processes behind the formation of structure in galactic clusters.
“In analyzing this diffused light, we find that the inner parts of the cluster are formed by a merger of massive galaxies, while the outer parts result from the accretion of galaxies similar to our Milky Way,” Montes said.
In addition, because the intracluster stars follow the gravitational pull of the cluster as a whole rather than that of individual galaxies, the light from these star beings provides an excellent way to study the distribution of dark matter in these clusters.
“The JWST 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 study co-author Trujillo.
The duo’s research was published Dec. 1 in the Astrophysical Journal Letters
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