Merger types forming the Virgo cluster in recent gigayears

TL;DR

This study uses cosmological simulations to analyze the merger history of Virgo-like galaxy clusters, revealing they typically experience few significant recent mergers and have a quiet accretion history, which helps understand galaxy evolution.

Contribution

It provides new insights into the recent merger history of Virgo-like clusters using simulations that replicate the local universe environment.

Findings

Virgo-like halos had on average only one major merger in the last four gigayears.

These halos have a quiet merging history over the last seven gigayears.

Virgo halos tend to accrete matter along a preferred direction.

Abstract

As our closest cluster-neighbor, the Virgo cluster of galaxies is intensely studied by observers to unravel the mysteries of galaxy evolution within clusters. At this stage, cosmological numerical simulations of the cluster are useful to efficiently test theories and calibrate model. However, it is not trivial to select the perfect simulacrum of the Virgo cluster to fairly compare in detail its observed and simulated galaxy populations that are affected by the type and history of the cluster. Determining precisely the properties of Virgo for a later selection of simulated clusters becomes essential. It is still not clear how to access some of these properties such as the past history of the Virgo cluster from current observations. Therefore, directly producing effective simulacra of the Virgo cluster is inevitable. Efficient simulacra of the Virgo cluster can be obtained via simulations that resemble the local Universe down to the cluster scale. In such simulations, Virgo-like halos form in the proper local environment and permit assessing the most probable formation history of the cluster. Studies based on these simulations have already revealed that the Virgo cluster has had a quiet merging history over the last seven gigayears and that the cluster accretes matter along a preferential direction. This paper reveals that in addition such Virgo halos have had on average only one merger larger than about a tenth of their mass at redshift zero within the last four gigayears. This second branch (by opposition to main branch) formed in a given sub-region and merged recently (within the last gigayear). These properties are not shared with a set of random halos within the same mass range. This study extends [truncated]