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Multiscale Rotational–Compressive Organization in Cosmological Baryonic Flows

Year: 2026
Type: article
Abstract: Recent cosmological simulations show that baryonic matter in the cosmic web develops shocks, filamentary accretion flows, shear layers, and rotational structures. Although large-scale structure is driven by gravitational instability, the role of rotational motions in organizing baryonic flows across scales remains incompletely understood. We investigate rotational–compressive dynamics in cosmological baryonic flows using public CAMELS hydrodynamic grids from the IllustrisTNG and SIMBA suites over several epochs. From the baryonic velocity field, we derive the vorticity and define the nonlinear diagnostic S ω = ∇ · ( u × ω ), the divergence of the Lamb vector. Vortical structures are preferentially associated with filaments, accretion interfaces, and overdense regions. For the SIMBA realization at z = 0, Helmholtz decomposition shows that approximately 64% of the resolved velocity power is solenoidal and 36% compressive, giving an integrated ratio of about 1.8. The vorticity and nonlinear-source spectra strengthen toward low redshift, and exhibit organized multiscale behavior in both suites. The statistics further show intermittent vorticity, strong enstrophy growth, and scale-dependent correlations between the nonlinear rotational–compressive source and baryonic density fluctuations. Similar signatures in IllustrisTNG and SIMBA, despite different feedback prescriptions, indicate that these trends are robust features of nonlinear baryonic evolution. Although the available resolution does not establish fully developed turbulence, the results provide quantitative evidence that rotational motions are an important emergent component of cosmic-web dynamics and contribute to the multiscale organization of baryonic matter.
DOI: 10.3847/1538-4357/ae9bba
Language: English
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7211942364
FWCI:
Cites: 30
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Related to: 10