Galaxy distribution and evolution around a sample of 2dF groups

TL;DR

This study investigates galaxy evolution and clustering around 2dF groups up to ten times their virial radius, revealing anisotropic patterns and their relation to galaxy types, aiding understanding of large-scale structure and evolution.

Contribution

It introduces a method to analyze galaxy distribution and anisotropy around groups, linking spatial patterns to galaxy evolution and dynamical states.

Findings

Anticorrelation between anisotropy and early-type galaxy fraction

Galaxy groups' dynamical states can be inferred from neighborhood analysis

Large-scale filamentary structures influence galaxy evolution

Abstract

We study galaxy evolution and spatial patterns in the surroundings of a sample of 2dF groups. Our aim is to find evidence of galaxy evolution and clustering out to 10 times the virial radius of the groups and so redefine their properties according to the spatial patterns in the fields and relate them to galaxy evolution. Group members and interlopers were redefined after the identification of gaps in the redshift distribution. We then used exploratory spatial statistics based on the second moment of the Ripley function to probe the anisotropy in the galaxy distribution around the groups. We found an important anticorrelation between anisotropy and the fraction of early-type galaxies in these fields. Our results illustrate how the dynamical state of galaxy groups can be ascertained by the systematic study of their neighborhoods.This is an important achievement, since the correct estimate of the extent to which galaxies are affected by the group environment and follow large-scale filamentary structure is relevant to understanding the process of galaxy clustering and evolution in the Universe.