利用最新Planck 2018、DESI DR2以及PantheonPlus&SH0ES观测数据检验含曲率的符号转换宇宙学模型
Testing a Sign-Switch Cosmological Model with Curvature through Latest Planck 2018, DESI DR2 and PantheonPlus\&SH0ES Observational Data
AI总结：
本研究扩展含符号转换暗能量的$\Lambda_{\rm s}$CDM模型加入曲率参数，结合多波段观测数据联合约束宇宙学参数，发现宇宙高度符合空间平坦性，该模型相对标准$\Lambda$CDM的观测支持较弱。
AI中文摘要：
我们在符号转换暗能量图景的框架内研究宇宙的空间几何，将近期提出的$\Lambda_{\rm s}$CDM模型进行扩展，纳入自由曲率参数$\Omega_k$。在该框架下，有效宇宙学常数在特征红移$z_{\dagger}$处经历从负值到正值的转变。我们利用最新的Planck 2018宇宙微波背景（CMB）数据、DESI DR2重子声学振荡（BAO）测量结果，以及PantheonPlus&SH0ES Ia型超新星样本，对空间曲率参数$\Omega_k$及其他宇宙学参数进行联合约束。我们发现，在$\Lambda_{\rm s}$CDM$+\Omega_k$和$\Lambda$CDM$+\Omega_k$两种框架下，仅使用Planck数据都略微倾向于闭合宇宙，不过空间平坦性仍完全处于允许的不确定度范围内。当纳入低红移探测数据后，曲率的约束被显著收紧。具体而言，完整的Pk18+DR2+PP&SH0ES数据集给出$\Lambda_{\rm s}$CDM模型的$\Omega_k = 0.0001 \pm 0.0014$，表明宇宙与空间平坦性高度一致。我们进一步分析了$\Omega_k$、$H_0$与$S_8$之间的相关性，发现纳入曲率和符号转换暗能量组分有助于稳定宇宙学参数估计，同时与当前观测约束保持兼容。使用AIC和贝叶斯证据进行的模型比较显示，相较于$\Lambda$CDM，$\Lambda_{\rm s}$CDM模型得到的观测支持尚不明确/较为微弱。
英文摘要：
We investigate the spatial geometry of the Universe within the framework of a sign-switch dark energy scenario by extending the recently proposed $Λ_{\rm s}$CDM model to include a free curvature parameter $Ω_k$.In this framework, the effective cosmological constant undergoes a transition from a negative to a positive value at a characteristic redshift $z_{\dagger}$. Using the latest Planck 2018 cosmic microwave background (CMB) data, DESI DR2 baryon acoustic oscillation (BAO) measurements, and the PantheonPlus\&SH0ES Type Ia supernova sample, we derive joint constraints on the spatial curvature parameter $Ω_k$ and other cosmological parameters. We find that Planck data itself slightly favors a closed universe within both the $Λ_{\rm s}$CDM$+Ω_k$ and $Λ$CDM$+Ω_k$ frameworks, although spatial flatness remains well within the allowed uncertainties. When low-redshift probes were included, the curvature constraints were significantly tightened. In particular, the full Pk18+DR2+PP\&SH0ES dataset yields $Ω_k = 0.0001 \pm 0.0014$ for the $Λ_{\rm s}$CDM model, indicating a universe that is remarkably consistent with spatial flatness. We further analyzed the correlations between $Ω_k$, $H_0$, and $S_8$, finding that the inclusion of curvature and a sign-switch dark energy component helps stabilize cosmological parameter estimates while remaining compatible with current observational constraints. Model comparison using AIC and Bayesian evidence shows that the $Λ_{\rm s}$CDM model receives inconclusive/weak observational support relative to $Λ$CDM.
