arXiv subjects
Publications and source records attributed to A. Stepanian.
It is shown that the concept of "negative mass" introduced by Farnes (2018) to describe the dark sector within a unifying theory with the negative cosmological constant contradicts both the essence of the General Relativity and the available observational data. A viable model with modified weak-field General Relativity is mentioned.
The common nature of dark matter and dark energy is argued in [1] based on the approach that the cosmological constant Λenters the weak-field General Relativity following from Newton theorem on the "sphere-point mass" equivalency [2]. Here we probe the Λ-gravity description of dark matter in galaxy systems, from pairs up to galaxy clusters using the data of various sources, i.e. of Local Supercluster galaxy surveys, gravity lensing and Planck satellite. The prediction that the cosmological constant has to be the lower limit for the weak-field Λobtained from galaxy systems of various degree of virialization is shown to be supported by those observations. The results therefore support the Λ-gravity nature of dark matter in the studied systems, implying that the positivity of the cosmological constant might be deduced decades ago from the dynamics of galaxies and galaxy clusters far before the cosmological SN surveys.
We consider further consequences of recently [1] revealed role of cosmological constant Λas of a physical constant, along with the gravitational one to define the gravity i.e. the General Relativity and its low-energy limit. We now show how Λ-constant affects the basic relations involving the Planck units and leads to emergence of a new dimensionless quantity (constant) which can be given cosmological information content. Within Conformal Cyclic Cosmology this approach implies the possibility of rescaling of physical constants from one aeon to another; the rescaling has to satisfy a condition involving Λand admitting group symmetry. The emerged dimensionless information constant enables to reduce the dynamics of the universe to an algorithm of discrete steps of information increase.
The recent study of the strong gravitational lens ESO 325-G004 [1] leads to a new possibility for testing General Relativity and its extensions. Such gravity lens observational studies can be instrumental for establishing a limitation on the precision of testing General Relativity in the weak-field regime and on the two gravity constants (the Newtonian and cosmological ones) as described in [2]. Namely, we predict a critical value for the involved weak-field parameter γ_{cr}=0.998 (for M= 1.5 10^{11} M_{\odot} lens mass and r=2 kpc light impact distance), which remarkably does not depend on any hypothetical variable but is determined only by well measured quantities. If the critical parameter γ_{cr} will be established at future observations, this will mark the first discrepancy with General Relativity of conventional weak-field Newtonian limit, directly linked to the nature of dark sector of the Universe.
The common nature of the dark sector - dark energy and dark matter - as shown in [1] follows readily from the consideration of generalized Newtonian potential as a weak-field General Relativity. That generalized potential satisfying the Newton's theorem on the equivalence of sphere's gravity and that of a point-mass located in its center, contains an additional constant which along with the gravitational constant is able to explain quantitatively both the dark energy (cosmological constant) and dark matter. So, gravity is defined not by one but two fundamental constants. We show that, the second constant is dimensional-independent and matter-uncoupled and hence is even more universal than the gravitational constant, thus affecting the strategy of observational studies of dark energy and of the search of dark matter.
In this paper we study anisotropic spherical polytropes within the framework of general relativity. Using the anisotropic Tolman-Oppenheimer-Volkov (TOV) equations, we explore the relativistic anisotropic Lane-Emden equations. We find how the anisotropic pressure affects the boundary conditions of these equations. Also we argue that the behaviour of physical quantities near the center of star changes in the presence of anisotropy. For constant density, a class of exact solution is derived with the aid of a new ansatz and its physical properties are discussed.