According to a new study published at Nature Astronomy, scientists have found evidence that some of the largest structures in the universe rotate.
The structure observed is a cosmic filament, which is a long, cylindrical structure made of dark matter acting as a kind of bridge between galaxy clusters. Such filaments are actually strands of a cosmic web through which galaxies are tuned into the cluster nodes.
Astrophysicist, Peng Wang of the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany, said of the findings:
"By mapping the motion of galaxies in these huge cosmic superhighways using the Sloan Digital Sky survey - a survey of hundreds of thousands of galaxies - we found a remarkable property of these filaments: they spin."
While being only a few light-years in diameter, the filaments are hundreds of light-years in length.
By carefully observing the light emitted from the galaxies on cosmic filament and comparing them to each other, astronomers found that galaxies on the side of the filament were redshifted compared to the other side. This is expected to happen when the galaxies are in vortical motion perpendicular to the filament's spine. This is what scientists call, Doppler shifting.
Cosmographer, Noam Libeskind of the AIP, explained:
"On these scales the galaxies within them are themselves just specks of dust. They move on helices or corkscrew-like orbits, circling around the middle of the filament while travelling along it. Such a spin has never been seen before on such enormous scales, and the implication is that there must be an as yet unknown physical mechanism responsible for torquing these objects."
By finding out what that mechanism is, astronomers could eventually find out how angular momentum is generated in the cosmos. According to cosmological models, in the early universe there was no rotation and matter was moving from less dense to more dense regions.
Tidal torque, a theory suggesting the presence of a shearing force might be indicative of that mechanism, however scientists do not know enough in order to consider it in building models of cosmic evolution.
As galaxies are connected by cosmic filaments, such structures play a crucial role in the formation and evolution of galaxies, including their rotation. But prior to the study, the idea that filaments themselves spin was only plausible in theory.
Discovering that filaments actually do spin, will assist us in getting closer to understanding the emergence of angular momentum in the Universe, as well as the role that the cosmic web plays in its regulation.
Libeskind noted:
"It's fantastic to see this confirmation that intergalactic filaments rotate in the real Universe, as well as in computer simulation."
[h/t: science alert]
COMMENTS