Causes of Energy Density Inhomogeneity in Energy Momentum Squared Gravity

IF 1.2 4区物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS Gravitation and Cosmology Pub Date : 2024-08-23 DOI:10.1134/s0202289324700269

Z. Yousaf, M. Z. Bhatti, A. Farhat

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Abstract

In the presence of an anisotropic fluid, we examine the irregularity factors for a spherically symmetric relativistic matter. In \(f(\mathcal{G},T^{2})\) gravity, we investigate the equations of motion and dynamical relations using a systematic construction, where \(T\) stands for the trace of the energy-momentum tensor, and \(\mathcal{G}\) is the Gauss–Bonnet term. With the use of the Weyl tensor, we examine two well-known differential equations that would lead to an analysis of the sources of inhomogeneities. In \(f(\mathcal{G},T^{2})\) gravity, the irregularity factors are investigated by taking specific cases in the adiabatic and non-adiabatic regimes. We find that the conformal tensor and additional curvature terms compromise inhomogeneity for a pressureless nonradiating fluid and an isotropic fluid. In contrast to other cases, for a nonradiating anisotropic fluid, we observe that the term \((\Pi+\mathcal{E})\) now accounts for the survival of density inhomogeneity, rather than just the Weyl tensor and the modified terms. The last case clearly illustrates how several components, namely, radiating terms, the fluid shear and the expansion scalar in the \(f(\mathcal{G},T^{2})\) framework, are accountable for the formation of inhomogeneities from a homogeneous state of the structure. In the case \(f(\mathcal{G},T^{2})=0\), all our results reduce to those of GR.

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能量动量平方引力中能量密度不均匀的原因

摘要在存在各向异性流体的情况下，我们研究了球对称相对论物质的不规则系数。在(f(\mathcal{G},T^{2})\)引力中，我们使用系统结构研究了运动方程和动力学关系，其中\(T\)代表能动张量的迹，\(\mathcal{G}\)是高斯-波奈项。利用韦尔张量，我们研究了两个众所周知的微分方程，它们将导致对不均匀性来源的分析。在（f(\mathcal{G},T^{2})\）引力中，我们通过绝热和非绝热状态下的具体案例研究了不规则因子。我们发现，对于无压非辐射流体和各向同性流体，共形张量和附加曲率项会影响不均匀性。与其他情况不同的是，对于非辐射各向异性流体，我们观察到项（(\Pi+\mathcal{E})\）现在解释了密度不均匀性的存续，而不仅仅是韦尔张量和修正项。最后一种情况清楚地说明了在\(f(\mathcal{G},T^{2})\)框架中，辐射项、流体剪切力和膨胀标量这几个部分是如何从结构的均质状态形成不均匀性的。在 \(f(\mathcal{G},T^{2})=0\) 的情况下，我们的所有结果都与 GR 的结果一致。

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来源期刊

Gravitation and Cosmology ASTRONOMY & ASTROPHYSICS-

CiteScore

1.70

自引率

22.20%

发文量

审稿时长

>12 weeks

期刊介绍： Gravitation and Cosmology is a peer-reviewed periodical, dealing with the full range of topics of gravitational physics and relativistic cosmology and published under the auspices of the Russian Gravitation Society and Peoplesâ€™ Friendship University of Russia. The journal publishes research papers, review articles and brief communications on the following fields: theoretical (classical and quantum) gravitation; relativistic astrophysics and cosmology, exact solutions and modern mathematical methods in gravitation and cosmology, including Lie groups, geometry and topology; unification theories including gravitation; fundamental physical constants and their possible variations; fundamental gravity experiments on Earth and in space; related topics. It also publishes selected old papers which have not lost their topicality but were previously published only in Russian and were not available to the worldwide research community

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