Astronomers have discovered over 40 hidden galaxies within the ancient web of the universe.

The unique location of the Web (or PKS 1138-262) and the connections formed during the early stages of galaxy protocluster formation have allowed astronomers to learn more about the processes involved in the formation of massive clusters in the early Universe. Moreover, they have even discovered its "embryo"—one of the largest quasars from that era.

There are many questions regarding the Web, but this protocluster is rightly considered a kind of laboratory for studying the processes of interaction and evolution of galaxies in dense environments, opening new opportunities for future research in astrophysics and cosmology.

Now, to thoroughly examine this window into the past of the Universe, an international research team led by astronomer Rhythm Shimakawa from Waseda University (Japan) conducted observations of the protocluster using narrowband imaging in the Paβ (Paschen-beta) emission line with the NIRCam camera mounted on the James Webb Space Telescope.

It is worth noting that the Paβ spectral line is considered an indicator of star formation in galaxies and is less affected by interstellar dust absorption compared to the more commonly known hydrogen-alpha (Hα) spectral line. The latter is observed in the spectra of emission nebulae and is used to study phenomena in the Sun's atmosphere, such as prominences.

As a result, the team of scientists identified 57 sources with excess emission in the Paβ line. Of these, 41 met the criteria to be considered candidates for full membership in the cluster, while 24 galaxies were observed for the first time. The findings of this research, presented in The Astrophysical Journal, significantly expand the current understanding of the protocluster's composition and demonstrate the effectiveness of using the Paβ line to detect distant galaxies with active star formation.

In turn, the authors of a second study led by astronomer Jose Manuel Pérez-Martínez from Tohoku University (Japan) combined NIRCam observations in the Paβ line with ground-based observations in the Hα line obtained using the Subaru telescope.

This approach allowed them to investigate the so-called interstellar absorption (the absorption and scattering of electromagnetic radiation by matter in interstellar space) and the rate of star formation in 43 galaxies that are part of the Web.

The results of the study, also published in The Astrophysical Journal, indicated that most galaxies have a Paβ/Hα ratio: this corresponds to standard conditions in star-forming regions. This means that the level of dust in most observed objects is comparable to that in galaxies of similar mass located outside the cluster.

Furthermore, the lack of correlation between the amount of dust in galaxies and their position in the Web suggests that dust formation processes in them are largely independent of the surrounding environment.

"These results imply that dust in the galaxies of the Web protocluster primarily forms through normal star formation processes, rather than as a result of the influence of the dense surrounding environment of the cluster, as was previously thought," the researchers concluded.

The discovery of new galaxies in the ancient protocluster, along with an understanding of the role of interstellar dust in star formation processes, allows for a more complete picture of the formation and evolution of large structures in the early Universe.

Astronomers noted that further observations of the Web and other protoclusters using the James Webb Space Telescope will enable the discovery of even more galaxies in the early Universe, as well as a better understanding of the processes that lead to the formation of "modern" galaxy clusters.

"We are on the brink of new discoveries that will change our understanding of structure formation in the Universe. The James Webb Space Observatory provides us with unprecedented opportunities to peer into the deep past of the cosmos," the scientists concluded.