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arXiv 2201.04629gr-qcastro-ph.CO
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暗能量能从变化的$G$和时空几何中出现吗?

Can Dark Energy Emerge from a Varying $G$ and Spacetime Geometry?

Ekim Taylan Hanımeli, Isaac Tutusaus, Brahim Lamine, Alain Blanchard

摘要:

宇宙的加速膨胀意味着存在一种被称为暗能量的能量贡献。这种暗能量与宇宙学标准模型中的宇宙学常数有关,其性质仍然未知。我们将讨论另一种引力模型,在这种模型中,由于爱因斯坦场方程中的引力常量$G$与时间有关,这种暗能量的贡献自然出现。通过这种修改,比安奇恒等式需要引入一个额外的张量场,以便满足通常的物质和辐射守恒方程。这个张量场的状态方程是使用额外的约束条件得到的,这些约束条件来自于这样的假设,即这个张量场表示对$G$变化的时空响应。我们还将提出这个模型的预测宇宙后期的数据,并表明,这个新的张量的能量贡献是能够解释宇宙的加速膨胀,而无需添加一个宇宙学常数。与许多其他引力强度不同的替代引力不同,预测的$G$演化也与当地观测结果一致,因此该模型不需要筛选。最后,我们将讨论这种方法可能对宇宙学和未来前景产生的其他影响。

英文摘要:

The accelerated expansion of the universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown. We will discuss an alternative gravity model in which this dark energy contribution emerges naturally, as a result of allowing for a time-dependence on the gravitational constant, $G$, in Einstein's field equations. With this modification, Bianchi's identities require an additional tensor field to be introduced so that the usual conservation equation for matter and radiation is satisfied. The equation of state of this tensor field is obtained using additional constraints, coming from the assumption that this tensor field represents the space-time response to the variation of $G$. We will also present the predictions of this model for the late-universe data, and show that the energy contribution of this new tensor is able to explain the accelerated expansion of the universe without the addition of a cosmological constant. Unlike many other alternative gravities with varying gravitational strength, the predicted $G$ evolution is also consistent with local observations and therefore this model does not require screening. We will finish by discussing possible other implications this approach might have for cosmology and some future prospects.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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