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arXiv 1807.07553gr-qc
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爱因斯坦-以太理论中的真空解

Vacuum solutions in the Einstein-Aether Theory

M. Campista, R. Chan, M. F. A. da Silva, O. Goldoni, V. H. Satheeshkumar, Jaime F. Villas da Rocha

摘要:

爱因斯坦-以太(EA)理论属于一类修正的引力理论,其特征在于引入了一个类时单位矢量场,称为以太。在这种情况下,一个优选的框架作为洛伦兹不变性被破坏的自然结果而出现。在目前的工作中,我们已经获得并分析了一些精确的解决方案,该理论允许的两个特殊情况下的完美流体,都与Friedmann-Lemaitre-Robertson-Walker(FLRW)对称性:(i)流体与恒定的能量密度($p=-ρ_0$),和(ii)流体与零能量密度($ρ_0=0$),相应的真空解决方案与宇宙学常数($Λ$),分别。我们的解表明,EA和GR理论不能仅通过耦合常数来区分对方。这种差异是清楚地表明,因为存在的奇异性,有没有在GR理论。这个特性出现在$p=-ρ_0$和$ρ_0=0$的解中,后者只依赖于以太场。此外,我们还考虑了Raychaudhuri方程中EA理论的项,讨论了这种情形下强能量条件的意义,发现这依赖于以太场。解决方案允许一个扩展或收缩系统。得到了一个反弹解、一个奇异解、一个常数解和一个加速膨胀解,从坍缩系统或宇宙学模型的动力学角度展示了EA理论的丰富性.考虑有效流体的能量条件的分析表明,在能量密度不变的情况下,乙醚项对系统的加速膨胀有显著的贡献。另一方面,对于真空情况($ρ_0=0$),对于醚流体,能量条件全部满足。

英文摘要:

The Einstein-Aether (EA) theory belongs to a class of modified gravity theories characterized by the introduction of a time-like unit vector field, called aether. In this scenario, a preferred frame arises as a natural consequence of a broken Lorentz invariance. In the present work we have obtained and analyzed some exact solutions allowed by this theory for two particular cases of perfect fluid, both with Friedmann-Lemaitre-Robertson-Walker (FLRW) symmetry: (i) a fluid with constant energy density ($p=-ρ_0$), and (ii) a fluid with zero energy density ($ρ_0=0$), corresponding to the vacuum solution with and without cosmological constant ($Λ$), respectively. Our solutions show that the EA and GR theories do not differentiate each other only by the coupling constants. This difference is clearly shown because of the existence of singularities that there are not in GR theory. This characteristic appears in the solutions with $p=-ρ_0$ as well as with $ρ_0=0$, where this last one depends only on the aether field. Besides, we consider the term of the EA theory in the Raychaudhuri equation and discuss the meaning of the strong energy condition in this scenario and found that this depends on aether field. The solutions admit an expanding or contracting system. A bounce, a singular, a constant and an accelerated expansion solutions were also obtained, exhibiting the richness of the EA theory from the dynamic point of view of a collapsing system or of a cosmological model. The analysis of energy conditions, considering an effective fluid shows that the term of the aether contributes significantly for the accelerated expansion of the system for the case in which the energy density is constant. On the other hand, for the vacuum case ($ρ_0=0$), the energy conditions are all satisfied for the aether fluid.

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