AI 中文总结
该研究利用SPHEREx全天巡天数据构建了紫外到近红外的类星体复合光谱，分析其连续谱和发射线特征，发现其幂律指数与类星体性质有关，线比符合预测，等效宽度与光度成正比，且光谱形状受宿主星系污染影响。
AI 中文摘要
我们展示了一个由∼61,000个1型SDSS类星体（中值红移z≈1.26）构成的复合光谱，它利用SPHEREx分光光度数据构建，覆盖0.14 - 4.5μm的静止帧波长范围。SPHEREx任务在102个近红外光谱通道（0.75 - 5.0μm）对全天进行巡天，光谱分辨率R≈35 - 130，为构建统计上稳健的类星体复合光谱提供了独特数据集。我们发现所得复合光谱的紫外和光学连续谱可用幂律fν∝ναν描述，最佳拟合光谱指数αν = -0.10，而近红外连续谱的最佳拟合指数为 -1.46。光学和近红外波段的幂律指数强烈依赖类星体性质。红外与光学通量比随AGN光度增加而降低，与后退环面模型预测一致。宽发射线的线比与B情况复合的预测相符，表明内部消光几乎可忽略。这些发射线的等效宽度与AGN光度成正比，与鲍德温效应预期趋势相反。最后，复合光谱形状对宿主星系污染敏感，后续科学应用时必须考虑。
英文摘要
We present a composite spectrum of $\sim 61,000$ type 1 SDSS QSOs (median $z \approx 1.26$), constructed using SPHEREx spectrophotometric data and covering a rest-frame wavelength range of $0.14-4.5~μ$m. The SPHEREx mission surveys the entire sky in 102 near-infrared spectral channels spanning $0.75-5.0~μ$m with a spectral resolution of $R \approx 35-130$, providing a unique dataset for building a statistically robust QSO composite. We find that the UV and optical continuum of the resulting composite can be described by a power law, $f_ν\propto ν^{α_ν}$, with a best-fit spectral index of $α_ν= -0.10$, while the near-infrared continuum is well-fit with a spectral index of $-1.46$. The power-law indices in both the optical and near-infrared regimes strongly depend on properties of QSOs, such that more luminous QSOs tend to exhibit flatter UV/optical and steeper near-infrared continua compared to those of less luminous ones. The IR-to-optical flux ratio decreases with increasing AGN luminosity, consistent with the predictions of the receding torus model. The line ratios of broad emission lines, including H$α$, Pa$β$, and Pa$α$, are in good agreement with predictions from Case B recombination, suggesting that internal extinction is almost negligible. The equivalent widths of these emission lines are proportional to AGN luminosity, contrary to the trend expected from the Baldwin effect. Finally, the shape of the composite is sensitive to host-galaxy contamination, which must be considered when utilizing this QSO composite for subsequent scientific applications.
Comments17 pages, 9 figures, submitted to ApJS
