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arXiv 2204.03335astro-ph.GA
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XQR-30样品中z~6类星体宽线区的化学观测

Chemical Abundance of z~6 Quasar Broad-Line Regions in the XQR-30 Sample

Samuel Lai, Fuyan Bian, Christopher A. Onken, Christian Wolf, Chiara Mazzucchelli, Eduardo Banados, Manuela Bischetti, Sarah E. I. Bosman, George Becker, Guido … 展开作者

Samuel Lai, Fuyan Bian, Christopher A. Onken, Christian Wolf, Chiara Mazzucchelli, Eduardo Banados, Manuela Bischetti, Sarah E. I. Bosman, George Becker, Guido Cupani, Valentina D'Odorico, Anna-Christina Eilers, Xiaohui Fan, Emanuele Paolo Farina, Masafusa Onoue, Jan-Torge Schindler, Fabian Walter, Feige Wang, Jinyi Yang, Yongda Zhu

摘要:

高红移类星体宽线区的元素丰度可以追溯早期宇宙中大质量星系核区的化学演化。本文研究了用VLT/X-shooter和Gemini/GNIRS观测到的25个高红移(5.8 < z < 7.5)类星体的静止坐标系紫外光谱中的金属敏感宽发射线通量比,这些类星体的黑洞质量在$\log(M_{\rm{BH}}/M_{\odot})= 8.4-9.8$以上,热光度在$\log(L_{\rm{bol}}/\rm{erg\, s}^{-1})= 46.7-47.7$以上。我们拟合了单个光谱和通过跨类星体属性的分箱产生的复合光谱:热光度,黑洞质量和\civ线的蓝移,通过比较我们的高红移类星体和文献中提出的低红移(2.0 < z < 5.0)结果,发现发射线比率没有红移演化。使用基于云的局部最优发射云光电离模型之间的金属丰度和发射线通量比的关系,我们发现宽发射线的可观测特性与金属丰度至少是太阳的2-4倍的气体云的发射一致。我们的高红移测量也证实了CIV发射线的蓝移与其等效宽度相关,这会影响对CIV归一化的线比。当占CIV蓝移,我们发现,休息帧的紫外线发射线通量比不相关的黑洞质量或热光度明显。

英文摘要:

The elemental abundances in the broad-line regions of high-redshift quasars trace the chemical evolution in the nuclear regions of massive galaxies in the early universe. In this work, we study metallicity-sensitive broad emission-line flux ratios in rest-frame UV spectra of 25 high-redshift (5.8 < z < 7.5) quasars observed with the VLT/X-shooter and Gemini/GNIRS instruments, ranging over $\log(M_{\rm{BH}}/M_{\odot})= 8.4-9.8$ in black hole mass and $\log(L_{\rm{bol}}/\rm{erg\, s}^{-1})= 46.7-47.7$ in bolometric luminosity. We fit individual spectra and composites generated by binning across quasar properties: bolometric luminosity, black hole mass, and blueshift of the \civ\, line, finding no redshift evolution in the emission-line ratios by comparing our high-redshift quasars to lower-redshift (2.0 < z < 5.0) results presented in the literature. Using Cloudy-based locally optimally-emitting cloud photoionisation model relations between metallicity and emission-line flux ratios, we find the observable properties of the broad emission lines to be consistent with emission from gas clouds with metallicity that are at least 2-4 times solar. Our high-redshift measurements also confirm that the blueshift of the CIV emission line is correlated with its equivalent width, which influences line ratios normalised against CIV. When accounting for the CIV blueshift, we find that the rest-frame UV emission-line flux ratios do not correlate appreciably with the black hole mass or bolometric luminosity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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