发表机构
Inter-University Centre for Astronomy & Astrophysics; Lawrence Berkeley National Laboratory（天文与天体物理大学间中心; 劳伦斯伯克利国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
基于DESI数据首次盲巡天发现3636个NaI吸收体，测量其发生率与质量密度随红移降低而增加约3.4倍，表明NaI示踪星系附近致密中性气体。
AI 中文摘要
我们利用暗能量光谱仪数据发布1的类星体光谱，展示了在过去约3 Gyr内介入NaI吸收体的首次盲统计巡天。我们在214,035条类星体视线方向上，在0.01≲z_abs≲0.27的红移范围内识别出3636个NaI D双线。我们通过端到端注入-恢复测试量化了巡天选择函数，并通过目视检查估计了残余污染。在NaI λ5891线的静止等值宽度W_5891≃0.95埃处，完备性达到50%，而目录加权纯度约为77%。对于0.95<W_5891<3.5埃的基准样本，我们测量了等值宽度分布（f(W_r)）、吸收体发生率（dN/dX）和宇宙NaI质量密度（Ω_NaI）。从z≃0.25到z≃0.03，dN/dX在按中位数W_5891=1.41埃划分的两个静止等值宽度子样本中均上升了约3.4倍，而Ω_NaI也增加了类似倍数。这对应于NaI吸收宿主星系共动数密度（n_com）与含NaI气体截面（σ_eff）之积随宇宙时间的平滑增长。Ω_NaI和dN/dX的相似演化表明每个吸收体的平均测量NaI柱密度变化很小。我们还发现了初步证据，表明NaI吸收体与前景星系在相对较小的投影距离上相关联，且其类星体视线方向比匹配的对照样本更红。这些结果支持NaI示踪星系内部及周围致密中性气体的图景。专门的星系巡天和CGM/ISM模拟可以检验推断的发生率和截面，而光谱叠加可以探测相关的气体和尘埃。
英文摘要
We present the first blind statistical survey of intervening NaI absorbers over the last $\simeq3$~Gyr using quasar spectra from the Dark Energy Spectroscopic Instrument Data Release~1. We identify 3636 NaI D doublets at $0.01\lesssim z_{\rm abs}\lesssim0.27$ along 214,035 quasar sightlines. We quantify the survey selection function through end-to-end injection--recovery tests and estimate the residual contamination from visual inspection. The completeness reaches 50% at a rest-equivalent width of the NaI $\lambda5891$ line, $W_{5891}\simeq0.95$ Angstrom, and the catalog-weighted purity is $\simeq77\%$. For the fiducial sample with $0.95<W_{5891}<3.5$ Angstrom, we measure the equivalent-width distribution ($f(W_r)$), absorber incidence ($dN/dX$), and cosmic NaI mass density ($Ω_{\rm Na\,I}$). From $z\simeq0.25$ to $z\simeq0.03$, $dN/dX$ rises by a factor of $\simeq3.4$ in both rest-equivalent-width subsamples, split at the median $W_{5891}=1.41$ Angstrom, while $Ω_{\rm Na\,I}$ increases by a similar factor. This corresponds to a smooth increase in the product of the comoving number density of NaI-absorbing hosts ($n_{\rm com}$) and the cross-section of the NaI-bearing gas ($σ_{\rm eff}$) with cosmic time. The similar evolution of $Ω_{\rm Na\,I}$ and $dN/dX$ indicates little change in the mean measured NaI column density per absorber. We also find preliminary evidence that NaI absorbers are associated with foreground galaxies at relatively small projected separations and that their quasar sightlines are redder than matched controls. These results support a picture in which NaI traces dense neutral gas in and around galaxies. Dedicated galaxy surveys and CGM/ISM simulations can test the inferred incidence and cross-section, while spectral stacking can probe the associated gas and dust.
CommentsSubmitted to AAS journals
