A Bound Violation on the Galaxy Group Scale: The Turn-Around Radius of NGC 5353/4

Abstract

The first observational evidence for the violation of the maximum turn-around radius on the galaxy group scale is presented. The NGC 5353/4 group is chosen as an ideal target for our investigation of the bound-violation because of its proximity, low-density environment, optimal mass scale, and existence of a nearby thin straight filament. Using the observational data on the line-of-sight velocities and three-dimensional distances of the filament galaxies located in the bound zone of the NGC 5353/4 group, we construct their radial velocity profile as a function of separation distance from the group center and then compare it to the analytic formula obtained empirically by Falco et al. (2014) to find the best-fit value of an adjustable parameter with the help of the maximum likelihood method. The turn-around radius of NGC 5353/4 is determined to be the separation distance where the adjusted analytic formula for the radial velocity profile yields zero. The estimated turn-around radius of NGC 5353/4 turns out to substantially exceed the upper limit predicted by the spherical model based on the LambdaCDM cosmology. Even when the restrictive condition of spherical symmetry is released, the estimated value is found to be only marginally consistent with the LambdaCDM expectation.

Published in ApJ, matched to the published version, 6 figures, 1 table

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• The Hubble flow around the CenA / M83 galaxy complex
• Galaxy Groups
• Midlife Crises in Dwarf Galaxies in the NGC 5353/4 Group
• Dynamics of astrophysical objects against the cosmological background
• A New Dynamical Mass Measurement for the Virgo Cluster using the Radial Velocity Profile of the Filament Galaxies

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• Relation between the Turnaround radius and virial mass in $f(R)$ model
• On the Universality of the Bound-Zone Peculiar Velocity Profile
• Effects of modified gravity on the turnaround radius in cosmology
• Turning Around along the Cosmic Web
• Cosmic structure sizes in generic dark energy models
• Estimating the Turn-Around Radii of Six Isolated Galaxy Groups in the Local Universe
• Distinguishing cosmologies using the turn-around radius near galaxy clusters
• Constraining phantom braneworld model from cosmic structure sizes
• Turnaround size of non-spherical structures
• Cosmological applications of the Brown-York quasilocal mass
• Turnaround physics beyond spherical symmetry
• The maximum turnaround radius for axisymmetric cosmic structures
• Turnaround radius in scalar-tensor gravity with quasilocal mass
• On the maximum volume of collapsing structures
• Independent Measurements of the Dynamical Masses of Six Galaxy Clusters in the Local Universe
• Searching for a signature of turnaround in galaxy clusters with convolutional neural networks