The largest galaxies in the Universe began to join in "chains" with their neighbors and line up 10 billion years ago, which makes their existence even more mysterious, astronomers say in an article published in the journal Nature Astronomy.
“This discovery is an important piece of this cosmic puzzle. It indicates that galaxies lined up in similar structures almost immediately after their appearance. We are now observing even dimmer and more distant galaxies in the hope of understanding whether this unusual property is characteristic of the even more distant past of the Universe,”says Michael West of Lowell Observatory in Flagstaff (USA).
Until recently, astronomers believed that most spiral galaxies are located inside clusters and rotated in relation to other objects inside them at random. Recent observations of the largest inhabitants of these clusters and galaxies inside neighboring clusters show that this is not so - most of them are elongated and turned towards their nearest neighbors, lining up in a kind of glowing filaments and lines.
Such behavior of galaxies, according to West, contradicts modern cosmological theories, which postulate that all visible and dark matter in the Universe was randomly distributed over it, due to the presence of microscopic fluctuations in the "echo" of the Big Bang. Therefore, galaxies and their clusters must be rotated and distributed in space in a similar way.
Some astronomers believed that there was really no contradiction here - they suggest that these "chains" of galaxies could have formed relatively recently in cosmic terms, in the last several billion years, thanks to the interactions of galaxies and their movements within clusters.
West and his team found hints that this was actually not the case by discovering an entire brood of ancient galaxies tilted toward nearby objects, observing the 65 galaxy clusters we see in the state they were about 10 billion years ago.
Analyzing images from the "Hubble" scientists have found in each of these clusters dozens of large galaxies, lined up with neighboring objects. In addition, astronomers have found similar but larger structures within neighboring clusters, indicating that galactic "chains" existed as early as 2-3 billion years after the birth of the universe.
These observations, as the authors of the discovery emphasize, do not exclude the possibility that galaxies could line up after their formation, but such "migrations" should be very fast, practically impossible from the point of view of theories about the origin and movement of galaxies and their clusters.
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To check whether this is so or not, scientists plan to observe even more distant galaxies that arose immediately after the end of the reionization era, the "dark ages" of the Universe. If they behave in the same way, then cosmologists will have to seriously think about how such an ordered structure of galaxies could have originated in a supposedly completely random universe.
