发表机构
Institute of Cosmology and Gravitation, University of Portsmouth; Scottish Universities Physics Alliance, University of Saint Andrews（朴茨茅斯大学宇宙学与引力研究所; 圣安德鲁斯大学苏格兰大学物理联盟）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用LAMOST和Gaia数据对247,103颗恒星进行年龄估计，通过MCMC重建得到最老恒星年龄为13.73 Gyr，与ΛCDM模型预测一致，对哈勃常数危机的新物理解决方案提出质疑。
AI 中文摘要
我们利用Xiang & Rix样本中的247,103颗银河系恒星（来自LAMOST DR7的高分辨率光谱和$Gaia$ eDR3视差）估计宇宙年龄。恒星年龄使用YY等时线估计，上限为20 Gyr。为了剔除年龄异常高且精确的恒星，我们要求年老恒星贫金属且富α元素。我们还要求YY年龄与仅基于$Gaia$数据的FLAME年龄一致。我们最终样本包含5 kpc内的155,600颗恒星，使用多种严格程度递增的技术提供一致的宇宙年龄估计。我们的主要结果使用MCMC重建潜在年龄分布，尽管迭代重建结果非常相似。采用创新方法处理MCMC重建及其不确定性，我们发现最老恒星的年龄为$A_\star = 13.73^{+0.18}_{-0.15}$ Gyr。改变质量筛选条件最多可将此值降至$A_\star = 13.31^{+0.21}_{-0.18}$ Gyr（使用更低的年龄依赖金属丰度上限）或升至$14.02^{+0.18}_{-0.15}$ Gyr（使用更高的上限）。我们推断的$A_\star$与CMB校准的ΛCDM模型预期的13.6 Gyr一致，假设第一批长寿命恒星在宇宙年龄0.2 Gyr时形成。这种一致性对仅通过复合前新物理解决哈勃张力的方案提出质疑，因为此类方案通常为了匹配低红移探针而给出宇宙年龄$12.9 \pm 0.2$ Gyr。考虑到我们样本中最老恒星的低金属丰度以及独立星震学约束，恒星建模不确定性很难将如此低的年龄与我们的结果调和。
英文摘要
We estimate the age of the Universe using the Xiang & Rix sample of 247,103 Milky Way stars with low-resolution spectroscopy from LAMOST DR7 and $Gaia$ eDR3 parallaxes. Stellar ages were estimated using YY isochrones up to 20 Gyr. We require consistency between YY ages and photometric FLAME ages based only on $Gaia$ data. To remove a population of stars with unusually low vertical action for their age, metallicity, and distance, we require old stars to be metal-poor and $α$-enriched. Our final sample of 146,810 stars within 5 kpc provides consistent cosmic age estimates using several techniques of increasing rigour. Our main results use an MCMC reconstruction of the latent age distribution, though our iterative reconstruction is very similar. Applying an innovative approach to our MCMC reconstruction and its uncertainties, we find that the oldest star has an age of $A_\star = 13.80^{+0.20}_{-0.16}$ Gyr. We conservatively estimate a systematic uncertainty of $\pm 0.4$ Gyr due to the choice of quality cuts, isochrone model, and initial helium abundance. Allowing 0.2 Gyr for the first long-lived stars to form, our inferred $A_\star$ is consistent with the 13.6 Gyr expected in CMB-calibrated $Λ$CDM. This agreement casts doubt on solutions to the Hubble tension solely through new physics prior to recombination, which generally imply a cosmic age of $12.9 \pm 0.2$ Gyr to match low redshift probes. It is difficult for stellar modelling uncertainties to reconcile such a low age with our result given the low metallicities of the oldest stars in our sample and independent asteroseismic constraints.
Comments39 pages, 3 tables, 35 figures. Revised in response to referee comments and resubmitted to the Monthly Notices of the Royal Astronomical Society in this form
