Sufficient conditions for a Lorentzian generalized quasi-Einstein manifold M,g,f,μ to be Robertson–Walker spacetime with Einstein fibers are derived. The Ricci tensor in this case gains the perfect fluid form. Likewise, it is proven that λ,n+m-Einstein M,g,w having harmonic Weyl tensor, ∇jw∇mwCjklm=0 and ∇lw∇lw<0 reduces fibers. Finally, if φ=−m∇lnw φRic-vector field on M an ψ=∇w ψRic-vector...

First and foremost, we show that a 4-dimensional conformally flat generalized Ricci recurrent spacetime $(GR)_4$ is an Einstein manifold. We examine such as solution of $f(R, G)$-gravity theory it shown the additional terms from modification gravitational sector can be expressed perfect fluid. Several energy conditions are investigated with G) = R +\sqrt{G}$ R^2+GlnG$. For both models, weak, nu...

Space-times admitting a 3-dimensional Lie group of conformal motions C3 acting on null orbits are studied. Coordinate expressions for the metric and the conformal Killing vectors (CKV) are provided (irrespectively of the matter content) and then all possible perfect fluid solutions are found, although none of these verify the weak and dominant energy conditions over the whole spacetime manifold...

In this work we study the properties of compact spheres made a charged perfect fluid with MIT bag model EoS for quark matter. Considering static spherically symmetric spacetime derive hydrostatic equilibrium equations in recently formulated four dimensional Einstein-Gauss-Bonnet ($4D$ EGB) gravity theory. setting, modified TOV are solved numerically aim to investigate impact electric charge on ...

The motive in this article is twofold. First we investigate the geometrical structures of a pseudo-symmetric spacetime (PS)4 with timelike vector under condition conformal flatness. We classify it into two possible types: constant Ricci scalar and closed velocity vector. Then further study type solutions F(R)-gravity theory demonstrate that pressure energy density effective cosmological perfect...

A sufficiently massive star in the end of its life will inevitably collapse into a black hole as more deconfined degrees freedom make core ever softer. One possible way to avoid singularity is by dimensional phase transition spacetime. Indeed, interior, two-dimensional (2D) nature, can be described well perfect fluid free massless Majorana fermions and gauge bosons under 2D supersymmetric mirro...

The paper aims to investigate curvature inheritance (CI) symmetry in M-projectively flat spacetimes. It is shown that the CI spacetime a conformal motion. We have proved M-projective tensor follows property along vector field ξ, when admits conditions of both and motion or ξ. Also, we derived some results for with perfect fluid following Einstein equations (EFEs) cosmological term admitting an ...

We developed the spacetime-covariant Hamilton principle for barotropic flows of a perfect fluid in external axial-vector potential conjugate to helicity current. Such carry helicity, chiral imbalance, controlled by axial potential. The interest such setting is motivated recent observation that axial-current anomaly quantum field theories with Dirac fermions appears as kinematic property classic...

The Euler equations for a non-homogeneous, non-viscous ~ompressible fluid are shown to be well-posed for a short time interval~ using techniques of infinite dimensional geometry and a weighted Hodge theorem. Regularity and other properties of these solutions are pointed out as well. !. Introduction. In [2], D. Ebin and the author introduced a technique for solving the Euler equations for a perf...

We study the problem of matching interior and exterior solutions to Einstein’s equations along a particular hypersurface. present main aspects C3 approach that involve third-order derivatives corresponding metric tensors in contrast standard C2 procedures known general relativity, which impose conditions on second-order only. The alternative does not depend coordinates allows us determine surfa...