AI 中文总结
本研究基于DESI DR2数据，测得Lyα森林的AP效应约束，结合BAO等数据给出宇宙学参数限制，为z>1处宇宙膨胀历史提供更精确锚定，缩小DESI与CMB的差异。
AI 中文摘要
我们利用暗能量光谱仪（DESI）第二次数据释放（DR2）测得的莱曼α（Lyα）森林关联函数的完整形状，给出Alcock-Paczyński（AP）测量结果。测量包含Lyα森林自关联及其与类星体交叉关联的信息，在有效红移z_eff=2.33处以1%的精度约束AP效应，精度是同一数据重子声学振荡（BAO）约束的两倍。结合Lyα的AP与BAO结果，测得横向共动距离比D_M(z_eff)/r_d=39.32±0.33、哈勃距离比D_H(z_eff)/r_d=8.600±0.066，其中D_M为横向共动距离，D_H为哈勃距离，r_d为拖曳 epoch的声视界。假设ΛCDM模型，Lyα森林测量结合核合成先验给出哈勃常数H₀=66.5±1.3 km s⁻¹ Mpc⁻¹的约束；Lyα的AP结果对应ΛCDM模型中物质分数Ω_m=0.325±0.018，比DESI BAO结果高1.4σ，这缩小了DESI结果与宇宙微波背景（CMB）的差异，从2.4σ降至2.2σ。我们结合DESI DR2 BAO与Lyα森林完整形状数据及外部数据集，给出扩展模型的更新约束；考虑由w₀和w_a参数化的随时间演化的暗能量状态方程时，DESI与CMB数据组合以2.7σ的显著性偏好该模型，加入超新星后显著性达3.2σ。新的Lyα AP测量使DESI给出了物质主导宇宙中z>1处膨胀历史的最精确锚定。
英文摘要
We present Alcock-Paczyński (AP) measurements from the full shape of Lyman-$α$ (Ly$α$) forest correlation functions measured from the second data release (DR2) of the Dark Energy Spectroscopic Instrument (DESI). Our measurements include information from the Ly$α$ forest auto-correlation and its cross-correlation with quasars. We constrain the AP effect with $1\%$ precision at an effective redshift $z_\mathrm{eff}=2.33$, which is twice as tight as the Baryon Acoustic Oscillation (BAO) constraint from the same data. When using the joint Ly$α$ AP and BAO results, we measure the ratios $D_\text{H}(z_\mathrm{eff})/r_\text{d}=8.600 \pm 0.066$ and $D_\text{M}(z_\mathrm{eff})/r_\text{d}=39.32 \pm 0.33$, where $D_\text{M}$ is the transverse comoving distance, $D_\text{H}$ is the Hubble distance, and $r_\text{d}$ is the sound horizon at the drag epoch. Assuming $Λ$CDM, Ly$α$ forest measurements combined with a nucleosynthesis prior produce a constraint on the Hubble constant $H_0=66.5\pm1.3\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$. The Ly$α$ AP result corresponds to a matter fraction constraint $Ω_\text{m}=0.325\pm0.018$ in $Λ$CDM, which is $1.4σ$ higher than DESI BAO. This impacts the DESI results relative to the Cosmic Microwave Background (CMB), slightly reducing their discrepancy from $2.4σ$ to $2.2σ$. We present updated constraints on extended models using the joint DESI DR2 BAO and Ly$α$ forest full shape data, together with external data sets. When considering a time-evolving dark energy equation of state parametrized by $w_0$ and $w_a$, we find it is preferred over $Λ$CDM at $2.7σ$ for the combination of DESI and CMB data, and at $3.2σ$ when also including supernovae. With the new Ly$α$ AP measurement, DESI provides its most precise anchor for the expansion history at $z > 1$ in the matter-dominated Universe.
