The ‘cosmic web’ hidden in the darkest reaches of the universe, seen like never before

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An immense network extends throughout our universe, a network composed of filaments that connect intergalactic space. This network remained hidden in the darkness, invisible to the detection mechanisms created by humanity. Until now.

Cosmic filaments. A team of astrophysicists has managed to “see” a network of filaments hidden in the vacuum of intergalactic space. The existence of this cosmic network, as it is usually called , was well known, but until now it had only been able to be detected in specific contexts, in regions “illuminated” by quasars. The new work allows us to visualize this immense structure that extends between galaxies.

“Before this discovery we had seen the filamentary structures under the equivalent of a streetlight,” astrophysicist Christopher Martin, one of the authors of the research, explained in a press release . “Now we can see them without a lamp.”

Dark matter and hydrogen. What exactly is this network? It is a network composed of filaments that extend between the galaxies of our cosmos. Along these filaments, hydrogen from intergalactic space accumulates and flows, uniting not only galaxies but also clusters of these .

What causes this gas to accumulate in these regions? Based on the dominant cosmological models, scientists believe that, rather than gas, these filaments would be composed of dark matter.

The architecture of our universe. This network is more than a road map, it is the vascular system through which the hydrogen reaches the galaxies and ends up condensing in certain regions where it fuels the birth of stars. It is estimated that about 60% of the hydrogen in our universe is found in this network.

“This cosmic web outlines the architecture of our universe,” explains Martin . “It is where most of the normal, or baryonic, matter of our galaxy resides and directly traces the location of dark matter.”

From the streetlight to the map. The cold, sparse hydrogen from these regions is difficult to observe, in contrast to the hydrogen that illuminates stars and other regions of the universe. The researchers achieved this by creating an instrument to search for Lyman-alpha emissions , the “spectral fingerprint” that hydrogen leaves when it absorbs and re-emits radiation.

This is how the Keck Cosmic Web Imager at the Keck Observatory, located in Hawaii, emerged. The researchers took advantage of the expansion of the universe and the associated phenomenon, redshift, to convert the images taken into three-dimensional maps of these filaments. Details of their work have been published in an article in the journal Nature Astronomy .

A look at the past. The map not only extends in space, but also in time since the scale of the mapped filaments covers regions about 10,000 or 12,000 million light years from our planet.

The work could be used to understand various aspects of the universe that surrounds us beyond the location of these filaments, perhaps the most important has to do with dark matter. This matter is present in a greater proportion in our universe than common or baryonic matter. Locating these filaments also helps us locate , at least in part, the dark matter of our cosmos.

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