How did the Virgo cluster form?

TL;DR

This study uses constrained cosmological simulations to investigate the formation history of the Virgo galaxy cluster, revealing a quiet accretion process over the last 7 billion years consistent with observations.

Contribution

It introduces a method to simulate the Virgo cluster's formation using galaxy peculiar velocities, providing new insights into its assembly history.

Findings

Virgo halos in simulations match observed properties within 10-20%.

Mass accretion occurred quietly over the last 7 Gyr.

Matter predominantly fell along the observed filament direction.

Abstract

While the Virgo cluster is the nearest galaxy cluster and therefore the best observed one, little is known about its formation history. In this paper, a set of cosmological simulations that resemble the Local Universe is used to shed the first light on this mystery. The initial conditions for these simulations are constrained with galaxy peculiar velocities of the second catalog of the Cosmicflows project using algorithms developed within the Constrained Local UniversE Simulation project. Boxes of 500 Mpc/h on a side are set to run a series of dark matter only constrained simulations. In each simulation, a unique dark matter halo can be reliably identified as Virgo's counterpart. The properties of these Virgo halos are in agreement at a 10-20% level with the global properties of the observed Virgo cluster. Their zero-velocity masses agree at one-sigma with the observational mass estimate. In all the simulations, the matter falls onto the Virgo objects along a preferential direction that corresponds to the observational filament and the slowest direction of collapse. A study of the mass accretion history of the Virgo candidates reveals the most likely formation history of the Virgo cluster, namely a quiet accretion over the last 7 Gigayears.