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arXiv 2501.07099astro-ph.CO
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利用宇宙计时钟和超新星数据对$\Lambda(t)$CDM宇宙学的约束

Constraints on $Λ(t)$CDM cosmology using Cosmic Chronometers and Supernova data

Yerlan Myrzakulov, M. Koussour, M. Bulanbay, S. Muminov, J. Rayimbaev

AI总结:

本研究在$\Lambda(t)$CDM宇宙学框架下,结合宇宙计时钟与Pantheon Ia型超新星数据,通过MCMC模拟约束动力学真空模型参数,验证了宇宙加速膨胀的动力学暗能量性质,给出了转变红移等关键宇宙学参数的约束结果。

摘要:

在本文中,我们在$\Lambda(t)$CDM宇宙学框架下研究了对动力学真空模型的约束,假设真空能密度的参数化形式为$\rho_\Lambda(t)=\rho_{\Lambda0} \left[1 + \alpha(1 - a)\right]$,其中$\rho_{\Lambda0}$为当前真空密度,$\alpha$为自由参数。我们使用31个宇宙计时钟数据点和1048个Pantheon Ia型超新星样本对模型参数进行约束,统计分析采用马尔可夫链蒙特卡洛(MCMC)模拟。研究发现宇宙当前正处于加速膨胀阶段,由减速阶段转变而来;由CC+SNe联合数据集得到的转变红移$z_t=0.65^{+0.03}_{-0.19}$与近期的约束结果一致。总物态方程显示宇宙处于加速阶段,物质和真空能的密度参数表现符合预期。$Om(z)$诊断量在不同数据集下表现出不同行为,当前加加速度参数值与$\Lambda$CDM模型略有偏差,但在不确定性范围内仍保持一致。这些发现支持暗能量的动力学性质,并为宇宙演化提供了有价值的约束。

英文摘要:

In this manuscript, we investigate the constraints on dynamical vacuum models within the framework of $Λ(t)$CDM cosmology by assuming a parameterization of the vacuum energy density as $ρ_Λ(t)=ρ_{Λ0} \left[1 + α(1 - a)\right]$, where $ρ_{Λ0}$ is the present vacuum density and $α$ is a free parameter. We use 31 cosmic chronometer data points and 1048 Pantheon type Ia supernova samples to constrain the model parameters. Our statistical analysis employs Markov Chain Monte Carlo (MCMC) simulations. We have found that the universe is currently undergoing accelerated expansion, transitioning from a decelerating phase. The transition redshift $z_t=0.65^{+0.03}_{-0.19}$ obtained from the combined CC+SNe dataset is consistent with recent constraints. The total EoS indicates an accelerating phase, with density parameters for matter and vacuum energy exhibiting expected behaviors. The $Om(z)$ diagnostic shows distinct behaviors for different datasets, and the present value of the jerk parameter deviates slightly from the $Λ$CDM model but remains consistent within uncertainties. These findings support the dynamic nature of dark energy and provide valuable constraints on the evolution of the universe.

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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