Dark energy domination in the Virgocentric flow

The standard \LambdaCDM 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. Can dark energy have strong dynamical effects on small cosmic scales as well as globally? Continuing our efforts to clarify this question, we focus now on the Virgo Cluster and the flow of expansion around it. 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. Our conclusions are: 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 \ga 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. 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, due to the nonlinear gravity-antigravity interplay with the dark energy dominating in the flow component.Comment: 7 pages, 2 figures, Astronomy and Astrophysics (accepted

Energy composition of the Universe: time-independent internal symmetry

The energy composition of the Universe, as emerged from the Type Ia supernova observations and the WMAP data, looks preposterously complex, -- but only at the first glance. In fact, its structure proves to be simple and regular. An analysis in terms of the Friedmann integral enables to recognize a remarkably simple time-independent covariant robust recipe of the cosmic mix: the numerical values of the Friedmann integral for vacuum, dark matter, baryons and radiation are approximately identical. The identity may be treated as a symmetry relation that unifies cosmic energies into a regular set, a quartet, with the Friedmann integral as its common genuine time-independent physical parameter. Such cosmic internal (non-geometrical) symmetry exists whenever cosmic energies themselves exist in nature. It is most natural for a finite Universe suggested by the WMAP data. A link to fundamental theory may be found under the assumption about a special significance of the electroweak energy scale in both particle physics and cosmology. A freeze-out model developed on this basis demonstrates that the physical nature of new symmetry might be due to the interplay between electroweak physics and gravity at the cosmic age of a few picoseconds. The big `hierarchy number' of particle physics represents the interplay in the model. This number quantifies the Friedmann integral and gives also a measure to some other basic cosmological figures and phenomena associated with new symmetry. In this way, cosmic internal symmetry provides a common ground for better understanding of old and recent problems that otherwise seem unrelated; the coincidence of the observed cosmic densities, the flatness of the co-moving space, the initial perturbations and their amplitude, the cosmic entropy are among them.Comment: 32 page

A reassessment of Phrynosuchus whaitsi Broom

Main articlePhrynosuchus whaitsi Broom 1913, from either the Tapinocephalu.s or Cistecephalus zones of .South Africa, is reassessed and is now considered nomen vanum due to the poor state of preservation of the specimen. The specimen shows some rhinesuchid characters, and is tentatively assigned to Rhinesuchus sp. indet. and in all probability is that of a juvenile.Non

Mode coupling in the modified betatron

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A new brachyopid, Batrachosuchus concordi sp. nov. from the Upper Luangwa Valley, Zambia with a redescription of Batrachosuchus browni Broom, 1903

Main articleTwo brachyopid skulls from southern Africa are described: one from the N'tawere Formation, Zambia is assigned to Batrachosuchus concordi sp. nov. and the other, B. browni Broom from the Cynognathus zone of South Africa is used as comparative material after further preparation had been effected on it. Both are assessed in relation to published descriptions of B. watsoni and it is concluded that B. concordi is closest to B. watsoni. The possibility that B. watsoni and B. browni belong to the same species is discounted for the present as there are four distinct differences in their skull morphology. Some poorly preserved and enigmatic bones from immediately behind the occiput of B. concordu are interpreted as limb and girdle elements. Associated with these bones are an axis and an atlas. All three species are at about the same level of organisation and that helps confirm that the Cynognathus zone of South Africa and the N'tawere Formation of Zambia are of approximately the same age and span the Lower-Middle Triassic boundary.Non

Three capitosaurs from the Triassic of South Africa: Parotosuchus africanus (Broom 1909); Kestrosaurus dreyeri Haughton 1925, and Parotosuchus dirus sp. Nov.

Main articleTwo members of the family Capitosauridae are redescribed after further preparation, namely Paratosuchus africanus (Broom 1909) and Kestrasaurus dreyeri Haughton, 1925. New material consisting of a fragmental, lower jaw or a very large parotosaur from the Cynognathus zone of Aliwal North is described, upon which a new species, Parotosuchus dirus, is erected. Paratosuchus africanus (Broom 1909) from the Cynognathus zone of Vaalbank, Albert, Cape Province, is redescribed and figured for the first time. It consists of most of the postorbital regions of the skull associated with part or the left lower jaw which are fairly well preserved and capable of being directly compared with the same parts of other taxa. Thus it is reconfirmed a valid member of the family Capitosauridae. Kestrosaurul dreyeri is re-examined and found to consist of large areas of plaster of Paris in which the original bone has been embedded. The entire skull could be about 5 cm shorter than the original reconstruction. The position and shape of the orbits are not preserved and the reconstructed lateral position found in the specimen is arbitrary. The parietal foramen is also not preserved. The nature of the preserved palate and occipital area indicates that the material probably represents a primitive member of the family Capitosauridae, not only stratrigraphically ( Lystrosaurus zone), but also morphologically. The taxonomic designation established by Welles and Cosgriff (1965) is retained. Kestrosaurus remains an enigma because it also displays certain trematosaurid characters. A partial capitosaurid jaw from the Cynognathus zone of Aliwal North, Cape Province, is also described which when reconstructed represents one of the largest amphibians found in Southern Africa. Comparisons are made with Parotosuchus pronus (Howie 1970) and Parotosuchus megarhinus (Chernin and Cosgriff 1975), which share a few similar characteristics. It is suggested that the amphibian represented by this jaw may be ancestral to both P. pronus and P. megarhinus. Based on substantial morphological differences in the symphysial and articular regions between this jaw and those of the above-mentioned parotosaurs, it is hereby proposed to erect a new species, Paratosuchus dirus (dirus = Latin: fearful), for this material.Non