论文标题
来自EBOSS数据的与Lyman-Alpha森林相关的金属线
Metal Lines Associated with the Lyman-alpha Forest from eBOSS Data
论文作者
论文摘要
我们研究了Eboss类星体光谱中与Ly $α$森林相关的金属物种。金属吸收系在堆叠的光谱中揭示了森林中选定的$α$吸收器的交叉谱系和通量波动场。鉴定出多达13种金属物种与相对较强的$α$吸收剂相关（$ -1.0 <δ_ {\ rmlyα} <-0.6 $以及中性氢柱密度约为$ 10^{15-16} $ $ \ $ \ $ \ rm cm^{ - 2} $ ymm cm^{ - 2} $ $ $ 2 { - 2} $ ABS} <4 $。这些物种的色谱柱密度降低了更高的红移和较弱的$ $α$吸收器。从对各种物种的色谱柱密度进行建模，我们发现色谱柱密度模式表明，在旁观培养基（CGM）和Galactic培养基（IGM）中的多个气体成分的贡献。虽然可以通过CGM的高密度，凉爽的气体（$ t \ sim 10^4 $ K）来解释低离子化物种（例如C II，SI II和MG II），但高电离物种可以居住在IGM中的低密度或高温气体。这些测量为模拟金属污染的输入提供了$α$ forest Baryon声学振荡测量的输入。与高分辨率类星体光谱中的金属吸收以及与流体动力星系形成模拟的比较可以进一步阐明这些LY $α$吸收器的物理条件。
We investigate the metal species associated with the Ly$α$ forest in the eBOSS quasar spectra. Metal absorption lines are revealed in the stacked spectra from cross-correlating the selected Ly$α$ absorbers in the forest and the flux fluctuation field. Up to 13 metal species are identified associated with relatively strong Ly$α$ absorbers (those with flux fluctuation $-1.0<δ_{\rm Lyα}<-0.6$ and with neutral hydrogen column density of ~ $10^{15-16}$ $\rm cm^{-2}$) over absorber redshift range of $2<z_{\rm abs}<4$. The column densities of these species decrease toward higher redshift and for weaker Ly$α$ absorbers. From modelling the column densities of various species, we find that the column density pattern suggests contributions from multiple gas components both in the circumgalactic medium (CGM) and in the intergalactic medium (IGM). While the low-ionization species (e.g., C II, Si II, and Mg II) can be explained by high-density, cool gas ($T \sim 10^4$ K) from the CGM, the high-ionization species may reside in low-density or high-temperature gas in the IGM. The measurements provide inputs to model metal contamination in the Ly$α$ forest baryon acoustic oscillations measurement. Comparison with metal absorptions in high-resolution quasar spectra and with hydrodynamic galaxy formation simulations can further elucidate the physical conditions of these Ly$α$ absorbers.
