Amazing stuff!
"The origin of spin in spiral and elliptical galaxies has posed a long-standing puzzle for astronomers. One idea, known as tidal torque theory, proposes that galaxies' spins are an imprinted record of the early universe, imparted by gravity long before galaxies first formed and still detectable in galaxies today.
Through new research ... a team ... has put that idea to its toughest test yet. ...
Tidal torque theory suggests the origins of this spin can be traced back to the earliest structures in the universe, when uneven clumps of gas and dark matter pulled on their neighbors.
If such a primordial clump were slightly elongated, tidal torque theory suggests it would feel gravity's pull more strongly on the end closest to a massive neighbor. This lopsided tug would set it rotating, a motion that its descendant galaxy should inherit. ...
To tackle this challenge, Sheng's team turned to data from the ELUCID project, which reconstructs the distribution of matter in the early universe based on the positions of galaxies we can see today. Using this reconstruction, they traced the pattern of spins seen in currently observable galaxies back to the primordial tidal forces that created them.
They then compared this prediction with real spin measurements gathered using an instrument that maps the motion of gas and stars within individual galaxies, for a substantial sample drawn from the nearby universe. ..."
From the abstract:
"Tidal-torque theory predicts that galaxy angular momenta are imprinted by the primordial tidal field acting on proto-structures and that they can retain information about the early Universe through cosmic evolution.
Here we test this prediction by comparing observed galaxy angular momentum vectors with those predicted from the primordial density field reconstructed by ELUCID for the nearby Universe.
Among the galaxy populations considered, the gas component of central massive elliptical galaxies provides the clearest signal, exhibiting a strong direction correlation at a significance of about 7σ.
These results provide robust observational evidence for tidal-torque theory and open a window for cosmological measurements of neutrino mass and other cosmological parameters."
A high-significance detection of primordial tidal torque imprints (no public access)
A high-significance detection of primordial tidal torque imprints (preprint, open access)
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