The influence of superstructures on bright galaxy environments: clustering properties

TL;DR

This study investigates how large-scale superstructures influence galaxy clustering, revealing that on large scales, environment affects clustering, but within virialized regions, clustering depends mainly on halo mass.

Contribution

It provides a comparative analysis of galaxy clustering inside and outside superstructures using observational data and semi-analytic models, highlighting the dominant role of halo mass within virialized regions.

Findings

Clustering differs significantly inside and outside superstructures at large scales.

Within 1 Mpc/h, clustering amplitudes are similar regardless of environment.

Galaxy clustering within virialized regions mainly depends on halo mass, not large-scale environment.

Abstract

We analyse the dependence of clustering properties of galaxies as a function of their large-scale environment. In order to characterize the environment on large scales, we use the catalogue of future virialized superstructures (FVS) by Luparello et al. and separate samples of luminous galaxies according to whether or not they belong to FVS. In order to avoid biases in the selection of galaxies, we have constructed different subsamples so that the distributions of luminosities and masses are comparable outside and within FVS. As expected, at large scales, there is a strong difference between the clustering of galaxies inside and outside FVS. However, this behaviour changes at scales r < 1 Mpc/h, where the correlations have similar amplitudes. The amplitude of the two-halo term of the correlation function for objects inside FVS does not depend on their mass, but rather on that of the FVS. This is confirmed by comparing this amplitude with that expected from extended Press-Schechter fits. In order to compare these observational results with current models for structure formation, we have performed a similar analysis using a semi-analytic implementation in a LCDM cosmological model. We find that the cross-correlation functions from the mock catalogue depend on the large-scale structures in a similar way to the observations. From our analysis, we conclude that the clustering of galaxies within the typical virialized regions of groups, mainly depends on the halo mass, irrespective of the large-scale environment.