paper

The invariance of group occupation across the cosmic web

arXiv:2509.09800 · doi:10.1051/0004-6361/202556548

Abstract

Recent efforts to identify secondary variations in the Halo Occupation Distribution (HOD) have primarily focused on simulations examining the role of large-scale cosmic environments such as superclusters, filaments, and underdense regions or voids. If present, these variations could yield valuable insights into galaxy formation mechanisms, halo assembly processes, and the influence of external factors on cosmic structure. We aim to test whether secondary trends in the HOD driven by the large-scale structure of the Universe are detectable observationally. In particular, we examine whether the HOD depends on distance to key features of the cosmic web by explicitly quantifying these spatial relationships. We also analyze whether HODs vary across different cosmic environments, defined by critical point classifications, and assess the influence of intrinsic galaxy properties such as central galaxy color. We create volume-limited galaxy samples from SDSS-DR18 and use a group catalog to determine halo masses and identify central and satellite membership. Additionally, we employ a DisPerSE catalog to locate critical points such as maxima, minima, and filaments in the cosmic web. We evaluate how the HOD varies with proximity to these features and across five distinct cosmic environments. We further examine trends related to the color of central galaxies and test the robustness of our results with alternative DisPerSE catalogs generated using different smoothing scales and persistence thresholds. Our analysis shows that large-scale environments only weakly influence the HOD. However, second-order dependencies may be revealed through a multivariate approach that combines local and large-scale metrics with intrinsic galaxy properties. Future work with next-generation surveys and advanced modeling may achieve the precision required to detect and characterize these subtle environmental correlations.

arXiv comment12 pages, 8 figures, submitted to A&A

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