A New Dynamical Mass Measurement for the Virgo Cluster using the Radial Velocity Profile of the Filament Galaxies

TL;DR

This study applies a novel filament-based dynamical mass estimation method to the Virgo cluster, deriving mass estimates that highlight the potential and limitations of using filament galaxy velocities for cluster mass measurements.

Contribution

The paper demonstrates the application of a simulation-based algorithm to real filament galaxy data around Virgo, providing new mass estimates and discussing systematic uncertainties.

Findings

Virgo cluster mass estimated as ~0.84 to 3.24 x 10^15 h^-1 M_sun

Method shows potential for dynamical mass measurement using filament velocities

Discussion of systematic uncertainties in the method

Abstract

The radial velocities of the galaxies in the vicinity of a cluster shows deviation from the pure Hubble flow due to their gravitational interaction with the cluster. According to a recent study of Falco et al. (2014) based on a high-resolution N-body simulation, the radial velocity profile of the galaxies located at distances larger than three times the virial radius of a neighbor cluster can be well approximated by a universal formula and could be reconstructed from direct observables provided that the galaxies are distributed along one dimensional filament. They suggested an algorithm for the estimation of the dynamic mass of a cluster $M_{\rm v}$ by fitting the universal formula from the simulation to the reconstructed radial velocity profile of the filament galaxies around the cluster from observations. We apply the algorithm to two narrow straight filaments (called the Filament A and B) that were identified recently by Kim et al. (2015) in the vicinity of the Virgo cluster from the NASA-Sloan-Atlas catalog. The dynamical mass of the Virgo cluster is estimated to be $M_{\rm v}=(0.84^{+2.75}_{-0.51})\times10^{15}\,h^{-1}M_{\odot}$ and $M_{\rm v}= (3.24^{+4.99}_{-1.31})\times 10^{15}\,h^{-1}M_{\odot}$ for the cases of the Filament A and B, respectively. We discuss observational and theoretical systematics intrinsic to the method of Falco et al. (2014) as well as the physical implication of the final results.