The largest rotating structure found in the universe

Artist’s impression of the cosmic filament: huge bridges of galaxies and dark matter connecting galaxy clusters to one another. The galaxies are guided in a corkscrew-like track in large clusters sitting at the ends. Their light appears to shift blue when they move towards us and shift red when they move away. Photo credit: AIP / A. Khalatyan / J. Fohlmeister

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By mapping the movement of galaxies in giant filaments connecting the cosmic web, astronomers at the Leibniz Institute for Astrophysics Potsdam (AIP), in collaboration with scientists in China and Estonia, discovered that these long galactic tendrils rotate on the order of hundreds of millions. light years. There has never been a rotation of such great proportions. Results published in Natural astronomy means that angular momentum can be generated in unprecedented magnitudes.

Cosmic filaments are huge bridges of galaxies and dark matter that connect galaxy clusters together. They channel galaxies into large clusters at their ends. “By mapping the movement of galaxies on this gigantic supercosmic highway with the Sloan Digital Sky survey – a survey of hundreds of thousands of galaxies – we discovered an extraordinary property of these filaments: they spin,” said Peng Wang, lead author of the book. published Studies and astronomers at AIP.

“Although they are thin cylinders – similar to pencils – hundreds of millions of light-years in length, but only a few million light-years in diameter, these fantastic threads of matter are spinning,” adds Noam Libeskind, project initiator at AIP. “At this scale, the galaxy itself is just a dust particle. They move on a spiral or track like a corkscrew and orbit the center of the filament as they move along it. Such rotation has never been seen on such a large scale before, and the implication is that there must be an unknown physical mechanism responsible for the torsion of these objects.”

How the angular momentum responsible for rotation is generated in a cosmological context is one of the main unsolved problems of cosmology. In the standard model of structure formation, the smaller densities that existed in the early universe grew due to gravitational instability as matter flowed from a less dense region to an overly dense region. Such potential flows are free of rotation or waves: In the early universe there was no primary rotation. Thus, each rotation must be created as a structure.

Cosmic webs in general and filaments in particular are closely related to the formation and evolution of galaxies. They also have a strong influence on the spin of galaxies and often govern the direction in which galaxies and their halos of dark matter rotate. However, it is not known whether current understanding of structure formation predicts that the filament itself, which is a non-collapse quasi-linear object, should spin.

Encouraged by the advice of theorist Dr. Mark Neyrinck that the filaments can rotate, we examined the distribution of the observed galaxies and looked for the rotation of the filaments,” said Noam Libeskind. “It’s incredible to see this confirmation that intergalactic filaments are rotating both in the real universe and in computer simulations.” Using an ingenious mapping method, the observed galaxy distribution was segmented into filaments. Each filament is approximated by a cylinder.

The galaxy within it is divided into two regions on either side of the filamentous spine (in projection) and the average redshift difference between the two regions is carefully measured. The mean redshift difference is a proxy for the velocity difference (Doppler shift) between the galaxies on the receding and approaching sides of the filament tube. With it he can measure the spin of the filament.

This study implies that depending on the angle of view and the mass of the endpoint, the filaments in the universe will show a clear signal consistent with rotation.