Volume 520, September-October 2010
|Number of page(s)||7|
|Section||Cosmology (including clusters of galaxies)|
|Published online||11 October 2010|
Dark energy domination in the Virgocentric flow
Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 21500 Piikkiö, Finland e-mail: email@example.com
2 Sternberg Astronomical Institute, Moscow University, Moscow 119899, Russia
3 Special Astrophysical Observatory, Nizhnii Arkhys 369167, Russia
4 University of Alabama, Tuscaloosa, AL 35487-0324, USA
Accepted: 1 June 2010
Context. The standard ΛCDM cosmological model implies that all celestial bodies are embedded in a perfectly uniform dark energy background, represented by Einstein's cosmological constant, and experience its repulsive antigravity action.
Aims. Can dark energy have strong dynamical effects on small cosmic scales as well as globally? Continuing our efforts to clarify this question, we now focus on the Virgo Cluster and the flow of expansion around it.
Methods. We interpret the Hubble diagram from a new database of velocities and distances of galaxies in the cluster and its environment, using a nonlinear analytical model, which incorporates the antigravity force in terms of Newtonian mechanics. The key parameter is the zero-gravity radius, the distance at which gravity and antigravity are in balance.
Results. 1. The interplay between the gravity of the cluster and the antigravity of the dark energy background determines the kinematical structure of the system and controls its evolution. 2. The gravity dominates the quasi-stationary bound cluster, while the antigravity controls the Virgocentric flow, bringing order and regularity to the flow, which reaches linearity and the global Hubble rate at distances 15 Mpc. 3. The cluster and the flow form a system similar to the Local Group and its outflow. In the velocity-distance diagram, the cluster-flow structure reproduces the group-flow structure with a scaling factor of about 10; the zero-gravity radius for the cluster system is also 10 times larger.
Conclusions. The phase and dynamical similarity of the systems on the scales of 1–30 Mpc suggests that a two-component pattern may be universal for groups and clusters: a quasi-stationary bound central component and an expanding outflow around it, caused by the nonlinear gravity-antigravity interplay with the dark energy dominating in the flow component.
Key words: Local Group / galaxies: clusters: individual: Virgo cluster / dark matter / dark energy
© ESO, 2010
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