Position of X-ray low surface brightness clusters in the cosmic filament network

¹ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan 1, 44001 Teruel, Spain
² INAF–Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
³ INAF–Osservatorio di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy

^⋆ Corresponding author; szarattini@cefca.es

Received: 25 October 2024
Accepted: 17 December 2024

Abstract

Aims. 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.

Methods. 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, are available in the literature. We computed the projected distance between each cluster and the spine of the nearest filament with the same redshift, and we investigated the link between this distance and the previously mentioned properties of the clusters, in particular their gas content.

Results. 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. 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 come from the same parent one. We speculate that the position of galaxy clusters within the cosmic web could have a direct impact on their gas mass fraction and hence on their X-ray surface brightness since the presence of a filament can hinder the outward flow of gas induced by the central active galactic nucleus (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.