暗能量与宇宙的负压缩性：基于宇宙状态方程的研究
Dark energy and negative compressibility of the Universe: A study based on cosmic equations of state
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中文总结 AI 辅助
本研究通过宇宙状态方程分析，揭示暗能量特征源于流体的负压缩性，而非异常性质，并强调将宇宙内容视为非理想流体系统的重要性。
中文摘要 AI 辅助
所有宇宙学模型都通过能量和物质来定义，这些能量和物质描述了目标宇宙的演化。无论其内容简单还是复杂，都可以通过一个有效的状态方程（EoS）来定义。我们通过分析其流体内容完整状态方程的性质，研究了不同的宇宙学模型。我们得到了压力$p$与能量密度$\rho$之比以及它们的导数$dp/d\rho$的一般表达式，这些表达式用减速参数和急动参数表示。我们表明，一般来说，其能量密度由多个理想气体构成的宇宙学无法用单一理想气体的状态方程来描述。这与宇宙演化过程中减速参数的变化直接相关。此外，我们研究了状态方程的有效压缩性性质，证明流体的暗能量特征应与其内容的负压缩性相关。这些特征取决于每个宇宙学系统的急动参数的动力学，这意味着暗能量演化的知识编码在尺度因子的三阶导数中。这种理解宇宙学模型性质的方法表明，某些模型（如$\Lambda$CDM模型或Chaplygin气体模型）的加速演化是由于其非理想内容流体的状态方程，而非相关的异常（暗能量）性质。相反，诸如$w$CDM、$w_0$$w_a$CDM或Dvali-Gabadadze-Porrati模型等模型，通过构造包含了具有异常内容的流体，这意味着负压缩性和有效的暗能量行为。我们的工作强调了将宇宙的所有内容视为具有唯一状态方程的非理想流体系统的重要性。
英文摘要
All cosmological models are defined through energy and matter, which describe the evolution of the targeted Universe. Whether the content is simple or complex, it can be defined through an effective equation of state (EoS). We study different cosmological models by analyzing the properties of the complete EoS of their fluid contents. We obtained general expressions for the ratio between pressure $p$ and energy density $ρ$, and for their derivative $dp/dρ$ in terms of deceleration and jerk parameters. We show that, in general, a cosmology whose energy density is constructed from multiple ideal gases cannot be described by the EoS of a single, ideal gas. This is directly related to a variation in the deceleration parameter during the evolution of the Universe. Furthermore, we studied the effective compressibility properties of the EoS, demonstrating that dark energy features of the fluid should be related to the negative compressibility of the contents. These features depend on the dynamics of the jerk parameter for each cosmological system, implying that the knowledge of dark energy evolution is encoded in the third-order derivatives of the scale factor. This approach to understanding the properties of cosmological models indicates that the accelerating evolution of some models, such as the lambda-cold dark matter model ($Λ$CDM) or the Chaplygin gas model, is due to the EoS of their nonideal content fluids rather than an associated anomalous (dark energy) nature. On the contrary, models such as $w$-cold dark matter ($w$CDM), $w_0$$w_a$-cold dark matter ($w_0$$w_a$CDM), or Dvali-Gabadadze-Porrati models, include by construction fluids with anomalous content, implying a negative compressibility and an effective dark energy behavior. Our work highlights the importance of treating all contents of the Universe as a nonideal fluid system, with a unique EoS.
发表机构
- Universidad Adolfo Ibáñez（阿道夫·伊巴涅斯大学）
- Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）
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