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

TL;DR

This study compares the properties of cosmic filaments identified using dark matter particles and galaxies in simulations, revealing differences in filament counts and structures depending on the tracer used.

Contribution

It introduces a detailed comparison of filament properties derived from dark matter and galaxy distributions within the same large-scale structure using the GAEA semi-analytic model.

Findings

Filaments based on different tracers generally agree but do not fully coincide.

Galaxy-based filament counts tend to underestimate those based on dark matter.

The physical properties of filaments are influenced by the choice of tracer.

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-analytic code GAEA 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 galaxies distribution is typically underestimated with respect to the corresponding dark matter filament extraction.