Galaxy evolution in the metric of the cosmic web

Abstract

The role of the cosmic web in shaping galaxy properties is investigated in\nthe GAMA spectroscopic survey in the redshift range $0.03 \\leq z \\leq 0.25$.\nThe stellar mass, $u - r$ dust corrected colour and specific star formation\nrate (sSFR) of galaxies are analysed as a function of their distances to the 3D\ncosmic web features, such as nodes, filaments and walls, as reconstructed by\nDisPerSE. Significant mass and type/colour gradients are found for the whole\npopulation, with more massive and/or passive galaxies being located closer to\nthe filament and wall than their less massive and/or star-forming counterparts.\nMass segregation persists among the star-forming population alone. The red\nfraction of galaxies increases when closing in on nodes, and on filaments\nregardless of the distance to nodes. Similarly, the star-forming population\nreddens (or lowers its sSFR) at fixed mass when closing in on filament,\nimplying that some quenching takes place. Comparable trends are also found in\nthe state-of-the-art hydrodynamical simulation Horizon-AGN. These results\nsuggest that on top of stellar mass and large-scale density, the traceless\ncomponent of the tides from the anisotropic large-scale environment also shapes\ngalactic properties. An extension of excursion theory accounting for\nfilamentary tides provides a qualitative explanation in terms of anisotropic\nassembly bias: at a given mass, the accretion rate varies with the orientation\nand distance to filaments. It also explains the absence of type/colour\ngradients in the data on smaller, non-linear scales.\n