论文标题
在宽线区域金属性中无红移的演变至Z = 7.54：Ulas J1342+0928的深度NIR光谱
No Redshift Evolution in the Broad Line Region Metallicity up to z=7.54: Deep NIR Spectroscopy of ULAS J1342+0928
论文作者
论文摘要
我们介绍了Ulas J1342+0928的深（9小时）Gemini-n/gnirs近红外光谱观测，z = 7.54时的发光类星体。检测到各种宽阔的发射线，以及在剩下的框架波长970-2930a上的基础连续性和铁森林。有一个清晰的趋势，高电离发射线显示了更大的蓝光，CIV1549表现为5510^{+240} _ { - 110} km S-1 blueshift，就远见[CII] 158UM发射线的系统红移。这些高电离线具有宽阔的FWHM S-1以上的概况。在频谱中确定的最低电离线中，也可以看到340^{+110} _ { - 80} km s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-s-km。 The updated MgII-based black hole mass of M_BH=9.1_{-1.3}^{+1.4} x 10^8 M_sun and the Eddington ratio of L_bol/L_Edd=1.1_{-0.2}^{+0.2} confirm that ULAS J1342+0928 is powered by a massive and actively accreting black hole.与在类似的亮度范围内的低红移类星体相比，发射线比（例如SIIV/CIV和ALIII/CIV）没有显着差异，这表明对宽线区域云的早期金属污染。这种趋势也适用于FEII/MGII线的比率，该趋势被称为宇宙时钟，可追溯到早期宇宙中的铁富集。使用不同的铁模板和连续拟合范围来探索FEII/MGII测量如何随光谱建模的函数而变化。需要在更高的红移或轻度光度范围内（L_BOL <10^46 ERG S-1）处的类星体来探测早期金属富集的位点以及FEII/MGII比的相应变化。
We present deep (9 hours) Gemini-N/GNIRS near-infrared spectroscopic observations of ULAS J1342+0928, a luminous quasar at z=7.54. Various broad emission lines were detected, as well as the underlying continuum and iron forests over the rest-frame wavelength 970-2930A. There is a clear trend that higher-ionization emission lines show larger blueshifts with CIV1549 exhibiting 5510^{+240}_{-110} km s-1 blueshift with respect to the systematic redshift from the far-infrared [CII] 158um emission line. Those high ionization lines have wide profiles with FWHM more than 10000 km s-1. A modest blueshift of 340^{+110}_{-80} km s-1 is also seen in MgII, the lowest ionization line identified in the spectrum. The updated MgII-based black hole mass of M_BH=9.1_{-1.3}^{+1.4} x 10^8 M_sun and the Eddington ratio of L_bol/L_Edd=1.1_{-0.2}^{+0.2} confirm that ULAS J1342+0928 is powered by a massive and actively accreting black hole. There is no significant difference in the emission line ratios such as SiIV/CIV and AlIII/CIV when compared to lower-redshift quasars in a similar luminosity range, which suggests early metal pollution of the broad-line-region clouds. This trend also holds for the FeII/MgII line ratio, known as a cosmic clock that traces the iron enrichment in the early universe. Different iron templates and continuum fitting ranges were used to explore how the FeII/MgII measurement changes as a function of spectral modeling. Quasars at even higher redshift or at fainter luminosity range (L_bol<10^46 erg s-1) are needed to probe the sites of early metal enrichment and a corresponding change in the FeII/MgII ratio.
