利用DESI DR2的多红移莱曼-α重子声学振荡探测物质主导的膨胀
Probing the matter-dominated expansion with multi-redshift Lyman-$α$ BAO from DESI DR2
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中文总结 AI 辅助
该研究利用DESI DR2的多红移Lyα森林数据进行BAO分析，通过特定方法在三个红移区间获得测量结果，验证了流程，得到了膨胀历史等相关参数，还给出聚类演化测量，结合其他测量提高了曲率约束。
中文摘要 AI 辅助
我们对DESI数据发布2（DR2）的莱曼-α（Lyα）森林进行了多红移重子声学振荡（BAO）分析，将森林自相关及其与类星体的交叉相关分为三个红移区间。我们在有效红移$z_{\rm eff}=2.13$、$2.40$和$2.81$处获得了BAO测量结果，每个区间在径向和横向方向上的精度约为2.0%-2.5%，对应各向同性BAO测量的精度约为1.1%-1.2%。使用与DESI DR2 Lyα BAO分析相同的数据产品和建模框架，我们在400个合成数据集上验证了该流程，发现能无偏恢复BAO且不确定性校准良好。测量结果显示各向同性膨胀参数$D_V/r_d$从$30.26\pm0.39$增加到$32.22\pm0.47$，阿尔科克-帕钦斯基参数$D_M/D_H$从$3.96\pm0.15$增加到$5.63^{+0.22}_{-0.24}$。哈勃距离$D_H/r_d$从$9.40\pm0.20$减小到$~7.22\pm0.17$，提供了与ΛCDM和预期物质主导标度一致的膨胀历史的直接测量，$H(z)\propto(1+z)^n$得出$n = 1.34\pm0.16$。红移划分还提供了聚类演化的自洽测量：Lyα森林偏差随$(1+z)^\gamma$演化，$\gamma_\alpha = 3.05\pm0.16$，RSD参数的红移演化由$\gamma_\beta = -0.97\pm0.26$描述，类星体偏差随$\gamma_Q = 1.56\pm0.23$演化，与独立的类星体聚类测量一致。将这三个区间的BAO测量结果与DESI DR2星系和类星体BAO测量结果相结合，在平坦的ΛCDM和$w_0w_a$CDM中产生了与单区间Lyα BAO分析一致的宇宙学约束，并在ΛCDM$+\Omega_K$中使曲率约束提高了约12%。
英文摘要
We present a multi-redshift Baryon Acoustic Oscillations (BAO) analysis of the DESI Data Release 2 (DR2) Lyman-$α$ (Ly$α$) forest, splitting the forest auto-correlation and its cross-correlation with quasars into three redshift bins. We obtain BAO measurements at effective redshifts $z_{\rm eff} = 2.13$, $2.40$, and $2.81$ with $\sim2.0$--$2.5\%$ precision per bin in the radial and transverse directions, corresponding to $\sim1.1$--$1.2\%$ precision for the isotropic BAO measurement. Using the same data products and modeling framework as the DESI DR2 Ly$α$ BAO analysis, we validate the pipeline on $400$ synthetic datasets and find unbiased BAO recovery with well-calibrated uncertainties. The measurements show an increase in the isotropic dilation parameter $D_V/r_d$ from $30.26\pm0.39$ to $32.22\pm0.47$ and in the Alcock-Paczyński parameter $D_M/D_H$ from $3.96\pm0.15$ to $5.63^{+0.22}_{-0.24}$. The Hubble distance $D_H/r_d$ decreases from $9.40\pm0.20$ to $7.22\pm0.17$, providing a direct measurement of the expansion history consistent with $Λ$CDM and the expected matter-dominated scaling, with $H(z)\propto(1+z)^n$ giving $n=1.34\pm0.16$. The redshift split also provides a self-consistent measurement of clustering evolution: the Ly$α$ forest bias evolves as $(1+z)^γ$ with $γ_α=3.05\pm0.16$, the RSD parameter has a redshift evolution described by $γ_β=-0.97\pm0.26$, and the quasar bias evolves with $γ_Q=1.56\pm0.23$, consistent with independent quasar clustering measurements. Combining these three-bin BAO measurements with DESI DR2 galaxy and quasar BAO measurements yields cosmological constraints consistent with the single-bin Ly$α$ BAO analysis in flat $Λ$CDM and $w_0w_a$CDM and improves curvature constraints by $\sim12\%$ in $Λ$CDM$+Ω_\mathrm{K}$.
