基于SDSS和DESI的1.0<z<3.5类星体的光度函数
Luminosity function of quasars at $1.0<z<3.5$ from SDSS and DESI
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中文总结 AI 辅助
本研究基于SDSS和DESI数据，采用新策略构建1.0<z<3.5类星体的光度函数，发现该区间类星体演化在低红移段适用纯光度演化模型，高红移段可适用纯光度或纯密度演化模型。
中文摘要 AI 辅助
我们开展了1.0<z<3.5的1型类星体演化研究，该红移区间覆盖了类星体活动的峰值时期。此前已有大量工作对类星体演化进行了广泛探索，但不同研究得到的类星体光度函数（QLFs）之间一致性不佳，推测是由不同类星体选择技术及对应的完备性校正引入的复杂性导致。我们采用一种基于所有已知类星体库构建QLFs的新策略，研究区域包括约1700平方度的宽场和约265平方度的深场，这些区域拥有主要来自SDSS和DESI的丰富光谱数据。随后我们应用静止帧紫外/光学波段的传统色选方法挑选类星体候选体，并利用类星体库对其进行证认。最终样本包含62426个1.0<z<3.5的类星体，色选的完备性约为96%，纯度约为93%，简单的色选方法可最大程度降低类星体演化研究中的选择偏差。我们推导了分箱QLFs，并采用双幂律模型对其进行表征，计算过程中样本不完备性和污染被作为不确定性的一部分考虑。与此前结果相比，我们的QLFs在暗端略高，且在2.5<z<3.5的亮端也更高。该QLFs表明，1.0<z<2.5的类星体演化可由纯光度演化模型很好地描述，而2.5<z<3.5的类星体演化可由纯光度演化模型或纯密度演化模型描述。
英文摘要
We present a study of the evolution of type 1 quasars at $1.0<z<3.5$, covering the peak epoch of quasar activity. The quasar evolution has been extensively explored by a variety of previous works and the derived quasar luminosity functions (QLFs) are not well consistent with each other, presumably due to the complexities introduced by different quasar selection techniques and associated completeness corrections. We use a new strategy to construct QLFs based on a library of all known quasars. We focus on a wide region of $\sim$1700 deg$^2$ and a deep field of $\sim$265 deg$^2$ that have rich spectroscopic data primarily from SDSS and DESI. We then apply traditional color cuts in the rest-frame UV/optical to select quasar candidates and use the quasar library to identify them. Our final sample consists of 62,426 quasars at $1.0<z<3.5$, with a high completeness ($\sim$96%) and a high purity ($\sim$93%) in the color selection. Simple color cuts can potentially minimize selection biases for the study of quasar evolution. We derive binned QLFs and characterize them using a double power-law model. Sample incompleteness and contamination are considered as part of the uncertainties in the calculation. Compared to previous results, our QLFs are slightly higher at the faint end, and also higher at the bright end at $2.5<z<3.5$. The QLFs suggest that the quasar evolution at $1.0 < z < 2.5$ can be well described by the pure luminosity evolution model, while at $2.5 < z < 3.5$, it can be described by either the pure luminosity evolution or the pure density evolution model.
