Proper projective collineation in non-static spherically symmetric space-times

Comments on matter collineations of plane symmetric, cylindrically symmetric and spherically symmetric spacetimes

Comments are made on some recently published papers on matter collineations of plane symmetric, cylindrically symmetric and spherically symmetric spacetimes.

Conformal Ricci collineations of static spherically symmetric spacetimes

Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when the Ricci tensor is non-degenerate, in which case the number of independent conformal Ricci collineations is \emph{fifteen}; the maximum number for 4-dimensional manifolds. In the degenerate case it is found that the static spherically symmetric spacetimes always have an infinite number of conformal Ricci collineations. Some examples are provided which admit non-trivial conformal Ricci collineations, and perfect fluid…

Matter Inheritance Symmetries of Spherically Symmetric Static Spacetimes

In this paper we discuss matter inheritance collineations by giving a complete classification of spherically symmetric static spacetimes by their matter inheritance symmetries. It is shown that when the energy-momentum tensor is degenerate, most of the cases yield infinite dimensional matter inheriting symmetries. It is worth mentioning here that two cases provide finite dimensional matter inheriting vectors even for the degenerate case. The non-degenerate case provides finite dimensional matter inheriting symmetries. We obtain different constraints on the energy-momentum tensor in each case. …

Matter Collineations of Static Spacetimes with Maximal Symmetric Transverse Spaces

This paper is devoted to study the symmetries of the energy-momentum tensor for the static spacetimes with maximal symmetric transverse spaces. We solve matter collineation equations for the four main cases by taking one, two, three and four non-zero components of the vector $ξ^a$. For one component non-zero, we obtain only one matter collineation for the non-degenerate case and for two components non-zero, the non-degenerate case yields maximum three matter collineations. When we take three components non-zero, we obtain three, four and five independent matter collineations for the non-degene…

Symmetries of the Energy-Momentum Tensor of Spherically Symmetric Lorentzian Manifolds

Matter collineations of spherically Symmetric Lorentzian Manifolds are considered. These are investigated when the energy-momentum tensor is non-degenerate and also when it is degenerate. We have classified spacetimes admitting higher symmetries and spacetimes admitting SO(3) as the maximal isometry group. For the non-degenerate case, we obtain either {\it four}, {\it six}, {\it seven} or {\it ten} independent matter collineations in which {\it four} are isometries and the rest are proper. The results of the previous paper [1] are recovered as a special case. It is worth noting that we have al…

Weyl Projective Curvature Symmetry in FRW k=0 Model

A study of proper Weyl projective curvature collineations in FRW k=0 space-time is given using the rank of Weyl projective curvature matrix and direct integration techniques. It is shown that a very special class of the above space-time admits proper Weyl projective curvature collineation.

Conformal symmetries of the energy-momentum tensor of spherically symmetric static spacetimes

Conformal matter collineations of the energy-momentum tensor for a general spherically symmetric static spacetime are studied. The general form of these collineations is found when the energy-momentum tensor is non-degenerate, and the maximum number of independent conformal matter collineations is \emph{fifteen}. In the degenerate case of the energy-momentum tensor it is found that these collineations have infinite degrees of freedom. In some subcases of degenerate energy-momentum, the Ricci tensor is non-degenerate, that is, there exist non-degenerate Ricci inheritance collineations.

关于广义相对论时空中M-射影曲率张量的若干性质

On some properties of M-projective curvature tensor in spacetime of general relativity

本文研究广义相对论时空中M-射影曲率张量的性质，推导其散度并引入M-射影共形运动对称性，给出时空容许该对称性的条件。

Projective collineations of decomposable spacetimes generated by the Lie point symmetries of geodesic equations

We investigate the relation of the Lie point symmetries for the geodesic equations with the collineations of decomposable spacetimes. We review previous results in the literature on the Lie point symmetries of the geodesic equations and we follow a previous proposed geometric construction approach for the symmetries of differential equations. In this study we prove that the projective collineations of a $\left( n+1\right) \,$% -dimensional decomposable Riemannian space are the Lie point symmetries for geodesic equations of the $n$-dimensional subspace. We demonstrate the application of our res…

Lie and Noether symmetries of geodesic equations and collineations

The Lie symmetries of the geodesic equations in a Riemannian space are computed in terms of the special projective group and its degenerates (affine vectors, homothetic vector and Killing vectors) of the metric. The Noether symmetries of the same equations are given in terms of the homothetic and the Killing vectors of the metric. It is shown that the geodesic equations in a Riemannian space admit three linear first integrals and two quadratic first integrals. We apply the results in the case of Einstein spaces, the Schwarzschild spacetime and the Friedman Robertson Walker spacetime. In each c…

球对称时空中的无穷远点的射影路径

Projective path to points at infinity in spherically symmetric spacetimes

本文利用分式线性映射构造球对称时空的射影边界，将无穷远拉至有限距离，并系统分析了史瓦西、Nariai、de Sitter 和 Godel 时空中测地线趋近无穷远点的行为。

带有自引力标量场的带电拓扑geon

Charged topological geons with a self-gravitating scalar field

本文研究由特定标量场支撑的静态球对称带电拓扑geon的性质，发现其引力质量由电荷和大小决定，提出该带电geon可作为超出标准模型的基本粒子（如暗物质）的经典模型。