标题： 一个从紫外到红外的 1 < z < 2 亮致密星复合体 显示英文标题

标题： An X-shooter composite of bright 1 < z < 2 quasars from UV to infrared

摘要： 类星体（QSO）光谱模板对类星体物理研究以及利用类星体作为探测介质气体和尘埃的工具都非常重要。然而，由不同时间、不同仪器组合的各种类星体样本以构建一个复合光谱并覆盖更宽的固有波长范围时，可能会产生系统效应，并且类星体宿主的贡献可能污染复合光谱。 我们基于从斯隆数字巡天（SDSS）中选出的红移 1 到 2.1 的明亮蓝光类星体构建了一个复合光谱。X-shooter 观测同时覆盖了紫外到近红外光，确保复合光谱涵盖了从 Lyman alpha (Ly$\beta$) 到 11350 Å$\AA$的完整固有波长范围，且没有显著的宿主星系污染。 假设复合光谱具有幂律连续性，我们发现光谱斜率为 $\alpha_\lambda$ = 1.70±0.01，比文献中之前的结果更陡峭。我们认为这种差异归因于我们更广的光谱波长覆盖范围，这使我们能够有效避免拟合受强类星体发射线（例如巴耳末线系和复杂的 [Fe II] 混合线）或宿主星系本征发射影响的区域。 最后，我们展示了类星体复合光谱在评估其他类星体消光中的应用。 显示英文摘要

摘要： Quasi-stellar object (QSO) spectral templates are important both to QSO physics and for investigations that use QSOs as probes of intervening gas and dust. However, combinations of various QSO samples obtained at different times and with different instruments so as to expand a composite and to cover a wider rest frame wavelength region may create systematic effects, and the contribution from QSO hosts may contaminate the composite. We have constructed a composite spectrum from luminous blue QSOs at 1 < z < 2.1 selected from the Sloan Digital Sky Survey (SDSS). The observations with X-shooter simultaneously cover ultraviolet (UV) to near- infrared (NIR) light, which ensures that the composite spectrum covers the full rest-frame range from Ly$\beta$ to 11350 $\AA$ without any significant host contamination. Assuming a power-law continuum for the composite we find a spectral slope of $\alpha_\lambda$ = 1.70+/-0.01, which is steeper than previously found in the literature. We attribute the differences to our broader spectral wavelength coverage, which allows us to effectively avoid fitting any regions that are affected either by strong QSO emissions lines (e.g., Balmer lines and complex [Fe II] blends) or by intrinsic host galaxy emission. Finally, we demonstrate the application of the QSO composite spectrum for evaluating the reddening in other QSOs.