Where do X-ray low surface brightness clusters sit with respect to filaments?

TL;DR

This study investigates the spatial distribution of gas-rich and gas-poor galaxy clusters relative to cosmic filaments, revealing trends in their distances that may influence their gas content and X-ray surface brightness.

Contribution

It provides the first analysis linking cluster positions within the cosmic web to their gas properties, highlighting potential environmental effects on cluster gas fractions.

Findings

Low surface brightness clusters are generally farther from filaments than high surface brightness ones.

Some low surface brightness clusters are found very close to filaments, within 2 Mpc.

Statistical tests do not conclusively prove different distributions for the two cluster types.

Abstract

The aim of this work is to study the position of gas-rich and gas-poor galaxy clusters within the large-scale structure and, in particular, their distance to filaments. Our sample is built from 29 of the 34 clusters in the X-ray unbiased cluster sample (XUCS), a velocity-dispersion-selected sample for which various properties, including masses, gas fractions, and X-ray surface brightness were available in the literature. We compute the projected distance between each cluster and the spine of the nearest filament with the same redshift and investigate the link between this distance and the previously-mentioned properties of the clusters, in particular with their gas content. The average distance between clusters and filaments is larger for low X-ray surface brightness clusters than for those of high surface brightness, with intermediate brightness clusters being an intermediate case. Also the minimum distance follows a similar trend, with rare cases of low surface brightness clusters found at distances smaller than 2 Mpc from the spine of filaments. However, the Kolmogorov-Smirnov statistical test is not able to exclude the null hypothesis that the two distributions are coming from the same parent one. We speculate that the position of galaxy clusters within the cosmic web could have a direct impact in their gas mass fraction, hence on its X-ray surface brightness, since the presence of a filament can oppose resistance to the outward flow of gas induced by the central AGN and reduce the time required for this gas to fall inward after the AGN is shut. However, a larger sample of clusters is needed in order to derive a statistically-robust conclusion