It may seem that all objects in our universe are scattered chaotically. But according to current models, massive objects such as galaxies and galaxy clusters are linked by strings of mysterious dark matter to form a vast “cosmic web” – a structure of hydrogen gas that feeds and facilitates galaxies. Interestingly, until now, no one has been able to directly observe the cosmic web or capture it in photographs. However, eight months of observation with the European Southern Observatory’s (ESO) Very Large Telescope and a year of careful study of the data allowed scientists to finally get a closer look at this incredible structure. The results showed that the mysterious galactic filaments supposedly appeared a couple of billion years after the Big Bang and are filled with billions of dwarf galaxies.
What is the cosmic web?
Astronomers have long assumed that billions of galaxies in the Universe are linked into a vast cosmic web of gas streams. But since this network practically does not emit light, it was extremely difficult to prove its existence, since it cannot be directly observed. Until now, astronomers have mapped only the nodes of this cosmic structure, highlighted by quasars.
Квазары – это наиболее яркий класс астрономических объектов в наблюдаемой Вселенной. Они излучают в тысячу раз больше энергии, чем весь Млечный Путь, в котором содержится по разным оценкам от 200 до 400 миллиардов звезд.
Another way to map the cosmic web on the map of the universe is gravitational lensing – with which astronomers look for the bending of light along its distant path, assuming that the thread of this giant structure is between the light source and us.
Today, researchers believe that galactic filaments intertwine, filling voids (from the English void – emptiness) – empty space and form the so-called “great walls” – relatively flat complexes of clusters and superclusters of galaxies. I told you more about them in this article.
How to detect the cosmic web?
Astronomers managed to see a piece of the cosmic web using the VLT – Very Large Telescope (ESA) equipped with a Multi Unit Spectroscopic Explorer (MUSE) 3D spectrograph. Together, these two instruments form one of the most powerful surveillance systems in the world. During the study, one section of the sky was viewed for more than 140 hours (about six nights from August 2018 to January 2019).
As a result, these powerful astronomical instruments were able to capture light from groups of stars and galaxies scattered by the gas filaments of the cosmic web. The authors of the scientific work note that this light was born about two billion years after the Big Bang. The VLT and MUSE images show the strands of the cosmic web located about 12 billion light-years from Earth.
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It is also interesting that computer simulations have shown that light is coming from billions of previously unseen dwarf galaxies, giving rise to trillions of stars. This large population of dwarf galaxies, the researchers note, feeds the hydrogen glow inside the filaments. The authors of the study, published in the journal Astronomy & Astrophysics, believe their discovery could fundamentally change the current understanding of galaxy formation in the early universe.
“After an initial period of darkness, the universe burst into light and produced a huge number of stars,” lead author of the study, astrophysicist Roland Bacon of the Center for Astrophysical Research in Lyon, told CNN. However, most of all scientists are interested in how this period of darkness in the Universe ended.
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As noted by Sciencealert.com, the researchers’ analysis shows that most of the hydrogen emissions in the universe can be explained by the large population of star-forming dwarf galaxies scattered along the filament. Of course, you cannot see them separately, since they are too far from the Earth. Yet astronomers hope that future research will help confirm the current discovery, which will undoubtedly lead to a revision of our understanding of the universe.
“If dwarf galaxies are also guided along the filaments of the cosmic web, like water droplets along a string, this may help explain how galaxies formed, grew and grew to enormous sizes in the early Universe,” the authors of the scientific paper write.
In addition, the search for radiation from star-forming dwarf galaxies could help scientists discover even more filaments of the cosmic web, and therefore bring humanity a new understanding that all objects in the observable universe are interconnected.