Dark, intergalactic network. A new way to study our universe

Scientists have discovered a new method of observing the universe. This is made possible by unique streams that utilize the intergalactic network. The new instrument allows for the analysis of the era when the first stars and black holes were formed.

The Keck Cosmic Web Imager, which is an original tool for exploring the cosmos, has for the first time allowed the observation of light emitted by the largest and most hidden part of the network of matter that connects galaxies. This groundbreaking discovery has opened a new method of observing the universe, as emphasized by astronomers.

Scientists from the American California Institute of Technology (Caltech) compare processes taking place in space to natural phenomena on Earth. Just as rivers provide water to the oceans, gas streams fuel galaxies scattered throughout the entire universe.

As specialists explain, galaxies are formed from spinning clouds of gas, which collapse under their own weight. This gas then condenses, leading to the formation of stars. This phenomenon makes galaxies visible to telescopes operating in various wave ranges.

Astronomers have long suspected that cold, dark filaments stretch between galaxies, supplying galaxies with gas. This gas is necessary for the formation of new stars. However, these streams, which are part of so-called cosmic web, are dark and difficult to see.

Despite astronomers knowing this network for many years, and even seeing the glow of its filaments around bright objects called quasars, they were unable to directly photograph the extending structures in the darkest areas of space dividing galaxies.

However, now, thanks to the Keck Cosmic Web Imager (KCWI), developed by the team of Prof. Christopher Martin from Caltech, this has been achieved. This device was installed in the Keck Observatory in Hawaii.

Prof. Martin, the author of the study described in the "Nature Astronomy" magazine, explains that the name Keck Cosmic Web Imager was chosen with the hope that this instrument will directly display the cosmic web. He expresses his satisfaction that these expectations have been met.

In 2015, Martin and his colleagues, with the help of this instrument, found strong evidence supporting the so-called cold flow theory. According to this theory, long filaments of the cosmic web penetrate galaxies and provide them with gas. At that time, one of the filaments was illuminated by a nearby quasar - the bright core of a young galaxy.

Now, scientists have learned to observe dark, unlit filaments. Prof. Martin explains that previously we saw filamentous structures as if under a lantern, but now we can see them even without it.

The researcher and his team have learned to record specific, weak waves emitted by the main component of filaments - hydrogen. The analysis of these waves, in conjunction with the change in their length accompanying the expansion of the universe, allows for the simultaneous determination of the distance from the studied filament.

- Essentially, we are creating a three-dimensional map of the cosmic network. We analyze spectra for every point in the image, in various wavelength ranges, and these lengths translate into distance - described Martin.

According to scientists, this has paved the way for entirely new observations of the universe. Mateusz Matuszewski, one of the scientists, says that thanks to KCRM, the new red channel operating in KCWI, they can reach even deeper into the past. He expresses his excitement about how this new instrument can help in analyzing more distant filaments and eras, when the first stars and black holes were formed.

Understanding the cosmic network will also allow for a better understanding of galaxy evolution and the distribution of dark matter in space.