by For the first time, astronomers have discovered dark matter suspended from giant filaments that stretch across the universe and form a “cosmic web” that holds galaxies together like the morning dew on a spider’s web.
Researchers from Yonsei University in Seoul, South Korea, used the Subaru Telescope — an 8.2-meter optical-infrared telescope near the summit of Maunakea in Hawaii — and the effect of gravity on light to indirectly observe dark matter in its sitting on cosmic web filaments in the Coma Cluster.
This is the first-ever detection of dark matter in the cosmic web, and could help confirm how this structure – with threads lasting thousands of light years – affected the evolution of the universe .
Also known as Abell 1656, the Coma Cluster is a collection of over a thousand galaxies located about 321 million light years away in the constellation Coma Berenices. This enormous size and relative proximity make the Coma Cluster an ideal place for scientists to hunt for dark matter on cosmic web threads.
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The cosmic web is a network of filaments, made up of matter, that feed gas into galaxies, helping them grow. This network also helps channel galaxies together, causing them to cluster.
The main filaments of the cosmic web are themselves the walls of the galaxy clusters, and the wall corresponding to the Coma Cluster known as the
“a fine wall.” The great wall was the first supermassive structure in the universe to be discovered.
Clusters of galaxies are believed to gather at points where they are crossed by filaments, but these filaments are believed to terminate between galaxies and form what are known as “intracluster filaments”. Dark matter is expected to move along these cosmic web filaments hanging from those interstellar filaments.
Dark matter as a cosmic scaffold
Although the cosmic web, the largest structure in the universe, has been known for decades, astronomers have only seen the faint glow of its gas filaments when illuminated by bright regions in the hearts of galaxies powered by black holes. fostering universities. Those active black holes are called quasars.
Last year, the Keck Cosmic Web Imager, also atop Maunakea, captured the first direct light emanating from the filaments of a smart web that intersect and stretch across the darkest corners of space. These are filaments that sit isolated between galaxies, in the largest and most hidden parts of the cosmic web.
“Seeing” a dark matter site around these cosmic web threads, however, is a completely different story.
That’s because, despite making up an estimated 85% of all matter in the universe, dark matter is invisible because it doesn’t interact with light like everyday matter that includes stars and dust.
The dominance of dark matter over ordinary matter also means that it dominates the filaments of the cosmic web, creating an invisible scaffolding on which the structure of the universe changes.
However, while dark matter does not interact with light, it does interact with gravity — and this interaction affects the movement of matter and the everyday light we see.
The team behind this research took advantage of this concept, using it to detect dark matter on the filaments of a cosmic web threaded throughout the Coma Cluster.
Albert Einstein’s 1915 theory of gravity, known as general relativity, suggests that objects with mass cause spacetime to curve. In turn, the theory explains, what we perceive as gravity arises from this curve. Furthermore, when light from a background source passes through this curve, its path is redirected.
This can result in background sources changing in the sky, zooming in, or in some extreme cases, even appearing at multiple points in the same image. This is called gravitational lensing.
So, using light from galaxies and stars behind the Coma Cluster and aided by the high sensitivity, high resolution and wide field of view of the Subaru telescope’s Hyper Suprime-Cam (HSC), the team detected the weak lensing effect of the dark matter component. intracluster filaments for the first time.
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This first-ever detection of dark matter in terminal parts of the cosmic web helps to further confirm that the large-scale structure is spreading across the universe.
The team’s findings were published in January in the journal Nature Astronomy.
