A continuous parameterization of the cosmic web

¹ CONICET-Universidad Nacional de Córdoba, Instituto de Astronomía Teórica y Experimental (IATE), Laprida 854, X5000BGR Córdoba, Argentina
² Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, X5000BGR Córdoba, Argentina
³ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D - 14482 Potsdam, Germany
⁴ Instituto de Astrofísica de La Plata (CCT La Plata, CONICET, UNLP), Observatorio Astronómico, Paseo del Bosque, 1900FWA La Plata, Argentina
⁵ Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata (UNLP), Observatorio Astronómico, Paseo del Bosque, B1900FWA La Plata, Argentina
⁶ Departamento de Física Teórica M-8, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
⁷ Centro de Investigación Avanzada en Física Fundamental (CIAFF), Universidad Autónoma de Madrid, E-28049 Madrid, Spain

^★ Corresponding author: yamila.yaryura@unc.edu.ar

Received: 3 February 2025
Accepted: 17 October 2025

Abstract

The intrinsic properties of galaxies are influenced by their environments, underscoring the environment’s critical role in galaxy formation and evolution. Traditionally, these environments are categorized into four fixed classifications: knots, filaments, walls, and voids, which collectively describe the complex organization of galaxies within large-scale structures. We propose an alternative description that complements the traditional quadripartite categorization by introducing a continuous framework, allowing for a more nuanced examination of the relationship between the intrinsic properties of galaxies and their environments. This complementary description is applied using one of the most prevalent methodologies: categorization using the eigenvalues of the Hessian matrix extracted from the matter density field. We integrated our findings into a semi-analytical model of galaxy formation, combined with cosmological numerical simulations, to analyze how the intrinsic properties of galaxies are influenced by environmental changes. In our study, we find a continuous distribution of eigenvalue ratios, revealing a clear dependence of galaxy properties on their surrounding environments. This method allowed us to identify critical values at which transitions in the behavior of key astrophysical galaxy properties become evident.