On the Alignment of Galaxies in Clusters

TL;DR

This study investigates the orientation of galaxies in isolated clusters, finding that galaxy alignment is more common in poorer clusters and decreases over time due to accretion and interactions.

Contribution

It provides new insights into galaxy alignment patterns in isolated clusters and how these patterns evolve with cluster density and galaxy interactions.

Findings

Galaxy alignment is more frequent in poor clusters.

Alignment decreases over time due to accretion and interactions.

Outer regions of clusters show less disturbed galaxy orientations.

Abstract

We explore the distribution of position angles (PA) of galaxies in clusters. We selected for study the isolated clusters, since the distribution of the galaxy orientation in clusters with close neighbors could be altered by gravitational influence of the latter. We assume that galaxies are aligned, if their number at one $90^o$ position angle interval is more than twice higher than at the other $90^o$ interval. We study the galaxy PA distribution at the outer regions of clusters with smaller space density, where the probability of the PA variation in the result of interactions between galaxies is smaller than at the dense central regions. We found that the alignment of galaxies is more often observed in poor clusters and concluded that originally galaxies were aligned, but in the result of accretion in time of field galaxies with arbitrary orientations and also due to the mutual interactions the relative number of aligned galaxies decreases.