Possible observational evidence that cosmic filaments spin

TL;DR

This study presents observational evidence suggesting that cosmic filaments of galaxies exhibit rotation, indicating that angular momentum generation occurs on scales much larger than previously understood, with implications for cosmic structure formation.

Contribution

The paper provides the first observational evidence that large-scale cosmic filaments spin, revealing a new scale of angular momentum in the universe.

Findings

Filaments show velocity patterns consistent with rotation.

Rotation strength depends on viewing angle and filament's dynamical state.

More massive haloes correlate with higher spin speeds.

Abstract

Most cosmological structures in the universe spin. Although structures in the universe form on a wide variety of scales from small dwarf galaxies to large super clusters, the generation of angular momentum across these scales is poorly understood. We have investigated the possibility that filaments of galaxies - cylindrical tendrils of matter hundreds of millions of light-years across, are themselves spinning. By stacking thousands of filaments together and examining the velocity of galaxies perpendicular to the filament's axis (via their red and blue shift), we have found that these objects too display motion consistent with rotation making them the largest objects known to have angular momentum. The strength of the rotation signal is directly dependent on the viewing angle and the dynamical state of the filament. Just as it is easiest to measure rotation in a spinning disk galaxy viewed edge on, so too is filament rotation clearly detected under similar geometric alignment. Furthermore, the mass of the haloes that sit at either end of the filaments also increases the spin speed. The more massive the haloes, the more rotation is detected. These results signify that angular momentum can be generated on unprecedented scales.