Mergers drive spin swings along the cosmic web

Abstract

The close relationship between mergers and the reorientation of the spin for galaxies and their host dark haloes is investigated using a cosmological hydrodynamical simulation (Horizon-AGN). Through a statistical analysis of merger trees, we show that spin swings are mainly driven by mergers along the filamentary structure of the cosmic web, and that these events account for the preferred perpendicular orientation of massive galaxies with respect to their nearest filament. By contrast, low-mass galaxies (M_s<10^10 M_sun at redshift 1.5) undergoing very few mergers, if at all, tend to possess a spin well aligned with their filament. Haloes follow the same trend as galaxies but display a greater sensitivity to smooth anisotropic accretion. The relative effect of mergers on spin magnitude is qualitatively different for minor and major mergers: mergers (and diffuse accretion) generally increase the magnitude of the angular momentum, but the most massive major mergers also give rise to a population of objects with less spin left. Without mergers secular accretion builds up the spin of galaxies but not that of haloes. It also (re)aligns galaxies with their filament.

5 pages, 5 figures, submitted to MNRAS

References in corpus (6)

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Cited by in corpus (22)

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• The SAMI Galaxy Survey: First detection of a transition in spin orientation with respect to cosmic filaments in the stellar kinematics of galaxies
• The build up of the correlation between halo spin and the large scale structure
• Bayesian analysis of the dynamic cosmic web in the SDSS galaxy survey
• The origin and properties of massive prolate galaxies in the Illustris simulation
• Alignment of galaxies relative to their local environment in SDSS-DR8
• The Imprint of Cosmic Web Quenching on Central Galaxies
• The large-scale environment from cosmological simulations I: The baryonic cosmic web
• Galaxy pairs align with galactic filaments
• The SAMI Galaxy Survey: flipping of the spin-filament alignment correlates most strongly with growth of the bulge
• MIGHTEE-HI: The relation between the HI gas in galaxies and the cosmic web
• Gas metallicity distributions in SDSS-IV MaNGA galaxies: what drives gradients and local trends?
• When galaxies align: intrinsic alignments of the progenitors of elliptical galaxies in the Horizon-AGN simulation
• Living with Neighbors. III. The Origin of the Spin$-$Orbit Alignment of Galaxy Pairs: A Neighbor versus the Large-scale Structure
• Cosmological evolution of orientations of cluster-sized dark matter haloes and their central galaxies in the Horizon-AGN simulation
• Real galaxy mergers from galaxy pair catalogs
• On the alignment of haloes, filaments and magnetic fields in the simulated cosmic web
• Gas accretion and Ram Pressure Stripping of Haloes in Void Walls
• Cosmological Signatures of Dark Sector Physics: The Evolution of Haloes and Spin Alignment
• The SAMI Galaxy Survey: The relationship between galaxy rotation and the motion of neighbours
• Caught in the web: galaxy mergers along cosmic filaments