Upper: density distribution of stacked satellite galaxies in Δx–Δy space relative to their central galaxies for the unwarped control sample (left), S-type warped galaxies (middle), and the residual map obtained by subtracting the control sample from the S-type distribution (right). White contours are drawn at 0.5σ intervals. An equal number of all stacked satellites, randomly selected from the control sample, is used as indicated. Larger and smaller black arrows mark the directions of the stronger and weaker warp sides, respectively. Lower: same as the upper panels, but for U-type warped galaxies. Credit: DOI: 10.3847/1538-4357/ae0e13

A research team led by Professor Woong-bae Zee at Sejong University has uncovered compelling evidence that the distinctive warped shapes of many disk galaxies are closely tied to both their surrounding satellite systems and the vast cosmic web in which they reside.

The findings are published in The Astrophysical Journal.

Using data from the Sloan Digital Sky Survey, researchers examined hundreds of warped galaxies—244 S-type and 127 U-type—along with their 1,373 and 740 satellite galaxies, respectively, and compared them with a carefully matched sample of unwarped systems.

To explore the connection between warps and their environments, the team analyzed the stacked spatial distribution of satellites around each type of galaxy. This approach served as an indirect, population-level probe of the underlying dark matter halo’s shape and orientation.

Their results show that warped galaxies display a pronounced anisotropy: satellites cluster preferentially at position angles between 45° and 90° from the galaxy’s major axis, with a peak excess probability near 0.003. In contrast, galaxies without warps exhibit nearly isotropic satellite distributions.

A schematic diagram of the relative orientation between DM halos and nearby large-scale filaments (gray shaded region) for S-type (red ellipse) and U-type (blue ellipse) warped galaxies. The figure highlights a characteristic difference in alignment: satellites around S-type warped galaxies tend to follow the direction of the nearest filament, while those around U-type warped galaxies are preferentially oriented perpendicular to the filament axis. Credit: DOI: 10.3847/1538-4357/ae0e13

The orientation of satellites relative to the cosmic web also differs depending on warp type. Around S-type warped galaxies, satellites tend to align with the nearest cosmic filament.

For U-type warps, satellites more often lie perpendicular to these filaments. Interestingly, the fraction of warped galaxies increases substantially in filament-rich environments within roughly 4 h⁻¹ Mpc of a filament, even though the total number of satellites per galaxy remains nearly constant regardless of distance to the filament.

Together, these findings challenge the idea that galactic warps form simply through random interactions with satellites. Instead, they point toward a more dynamic and structured origin, shaped by anisotropic tidal forces and the angular-momentum coupling between nonspherical dark matter halos and the surrounding cosmic web.

Upper: probability density function, P(Δθ), of the misalignment angle between the mean orientation of satellite distributions (θS-F, solid thick line) and the major axis of central edge-on disk galaxies (θC-F, dashed line) relative to the direction of the nearest filament for the unwarped sample (black), S-type (red), and U-type (blue). The shaded region represents Poisson errors for each bin. For comparison, the expected isotropic distribution with the same number of central and satellite galaxies is shown as a gray horizontal line, while the 3σ range of its random distribution is shaded in gray. Lower: same as upper panels, but for central galaxies that host at least six satellites (Nsat ≥ 6). Credit: DOI: 10.3847/1538-4357/ae0e13

The differences observed between S-type and U-type warps suggest that they may represent distinct evolutionary phases or reflect variations in their cosmic accretion histories.

The study adds an important new piece to the puzzle of how galaxies evolve within the intricate scaffolding of the universe’s large-scale structure.

More information: Woong-Bae G. Zee et al, Warped Disk Galaxies. II. From the Cosmic Web to the Galactic Warp, The Astrophysical Journal (2025). DOI: 10.3847/1538-4357/ae0e13

Citation: Warped galaxies linked to satellite patterns and cosmic web alignment (2025, December 10) retrieved 10 December 2025 from https://phys.org/news/2025-12-warped-galaxies-linked-satellite-patterns.html

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