Reports on Mathematical Physics ( IF 0.8 ) Pub Date : 2023-02-20 , DOI: 10.1016/s0034-4877(23)00013-7 Uday Chand De , Sameh Shenawy , Abdallah Abdelhameed Syied
Generalized Ricci recurrent spacetimes (GR)n are investigated in Gray's seven subspaces. It is proved that a (GR)n spacetime in all subspaces but one is an Einstein spacetime. The subspace cannot contain a (GR)n spacetime. Further, the subspaces and reduce to and , respectively. Next, we prove that a (GR)n spacetime is Ricci semi-symmetric if and only if either the spacetime is Einstein or the vector field Al is closed. Further, it is shown that the Ricci tensor of (GR)n is Riemann compatible if Al is closed. Finally, sufficient conditions are given on a (GR)n warped product manifold to guarantee that the factor manifolds are Einstein. Moreover, it is shown that a generalized Ricci recurrent GRW spacetime is an Einstein spacetime.
中文翻译:
广义 RICCI 循环时空的 GRAY 分解和翘曲积
在 Gray 的七个子空间中研究了广义 Ricci 循环时空 (GR) n 。证明所有子空间中的一个(GR) n时空只有一个是爱因斯坦时空。子空间不能包含 (GR) n时空。此外,子空间和减少到和, 分别。接下来,我们证明 a (GR) n时空是 Ricci 半对称当且仅当时空是爱因斯坦或矢量场A l是闭合的。此外,如果A l闭合,则表明 (GR) n的 Ricci 张量是黎曼相容的。最后,在 (GR) n翘曲乘积流形上给出充分条件以保证因子流形是爱因斯坦。此外,证明广义 Ricci 循环 GRW 时空是爱因斯坦时空。