论文标题
低密度HI HI间介质从z = 3.6到0的演变：数据，传输通量和HI柱密度
The evolution of the low-density HI intergalactic medium from z=3.6 to 0: Data, transmitted flux and HI column density
论文作者
论文摘要
我们介绍了低密度IgM中HI传输通量（F）和HI柱密度（N（HI））分布的新的均匀分析，该分布是Redshift Z的函数，用于0 <Z <3.6，使用55 hst/cos fuv（delta（z）= 7.2在z <0.5），五hst/stis+cos nuv（z <0.5），五hst/stis+cos nuv（z）和24 Keck/Hires（Delta（Z）= 11.6 at 1.7 <Z <3.6）Agn光谱。我们进行了一致，均匀的VOIGT曲线分析，以将光谱与不同的仪器相结合，以减少系统学并去除金属线污染。我们通过改进Z〜1时的测量值，以尤其是在牢固的定量基础上确认以前已知的结论。在0 <f <1处的两个通量统计，平均HI通量和通量概率分布函数（PDF）表明，相当大的进化发生在Z = 3.6到Z = 1.5，此后它会减慢以有效地稳定Z <0.5。但是，有较大的视线变化。对于HI柱密度分布函数（CDDF，F，f向n（hi）^（ - beta））在log（n（hi）/1cm^-2）= [13.5，16.0]处，beta随着z从beta〜1.60降低到z〜3.4时的beta 〜1.60，beta 〜1.82在z〜0.1处beta〜1.82。较低红移的CDDF形状可以通过少量的高Z CDDF的顺时针旋转来重现，而CDDF归一定更大。每个Z（DN/DZ）的吸收线数在Z〜1.5时显示出类似的进化中断，如通量统计所示。与低N（HI）吸收器相比，高N（HI）吸收剂的进化速度更快，以减少数量或横截面。单个DN/DZ在给定的z处显示出较大的散射。散射向较低的z增加，可能是由于较低z处的较强聚类引起的。
We present a new, uniform analysis of the HI transmitted flux (F) and HI column density (N(HI)) distribution in the low-density IGM as a function of redshift z for 0<z<3.6 using 55 HST/COS FUV (Delta(z)=7.2 at z<0.5), five HST/STIS+COS NUV (Delta(z)=1.3 at z~1) and 24 VLT/UVES and Keck/HIRES (Delta(z)=11.6 at 1.7<z<3.6) AGN spectra. We performed a consistent, uniform Voigt profile analysis to combine spectra taken with different instruments, to reduce systematics and to remove metal-line contamination. We confirm previously known conclusions on firmer quantitative grounds in particular by improving the measurements at z~1. Two flux statistics at 0<F<1, the mean HI flux and the flux probability distribution function (PDF), show that considerable evolution occurs from z=3.6 to z=1.5, after which it slows down to become effectively stable for z<0.5. However, there are large sightline variations. For the HI column density distribution function (CDDF, f proptional to N(HI)^(-beta)) at log (N(HI)/1cm^-2)=[13.5, 16.0], beta increases as z decreases from beta~1.60 at z~3.4 to beta~1.82 at z~0.1. The CDDF shape at lower redshifts can be reproduced by a small amount of clockwise rotation of a higher-z CDDF with a slightly larger CDDF normalisation. The absorption line number per z (dn/dz) shows a similar evolutionary break at z~1.5 as seen in the flux statistics. High-N(HI) absorbers evolve more rapidly than low-N(HI) absorbers to decrease in number or cross-section with time. The individual dn/dz shows a large scatter at a given z. The scatter increases toward lower z, possibly caused by a stronger clustering at lower z.
