The filament determination depends on the tracer: comparing filaments based on dark matter particles and galaxies in the gaea semi-analytical model

Abstract

ABSTRACT Filaments are elongated structures that connect groups and clusters of galaxies and are visually the striking feature in cosmological maps. In the literature, typically filaments are defined only using galaxies, assuming that these are good tracers of the dark matter distribution, despite the fact that galaxies are a biased indicator. Here, we apply the topological filament extractor disperse to the predictions of the semi-analytical code GAlaxy Evolution and Assembly to investigate the correspondence between the properties of z = 0 filaments extracted using the distribution of dark matter and the distribution of model galaxies evolving within the same large-scale structure. We focus on filaments around massive clusters with a mass comparable to Virgo and Coma, with the intent of investigating the influence of massive systems and their feeding filamentary structure on the physical properties of galaxies. We apply different methods to compare the properties of filaments based on the different tracers and study how the sample selection impacts the extraction. Overall, filaments extracted using different tracers agree, although they never coincide totally. We also find that the number of filaments ending up in the massive clusters identified using galaxy distribution is typically underestimated with respect to the corresponding dark matter filament extraction.