标题： 关于小红点和活动星系核的选择与颜色的研究 显示英文标题

标题： An Investigation Into The Selection and Colors of Little Red Dots and Active Galactic Nuclei

摘要： 近期，在詹姆斯韦伯太空望远镜（JWST）的星系外巡天中发现了大量在$z > 4$波段具有蓝色紫外斜率和极端红色静止框架光学斜率的紧凑源。 作为这些源的一个子样本，通常被称为“小红点”(LRDs)，已经被光谱观测发现其拥有宽线活动星系核（AGN），因此成为多个近期研究的重点，试图理解它们紫外和光学发射的起源。 在这里，我们从文献中整理出一个包含123个LRD的样本，连同JWST识别的AGN光谱和测光样本，以比较它们的颜色和光谱斜率。 我们发现，虽然在$z < 6$处的隐藏AGN与LRD的颜色高度不同，但在$z < 6$处的未隐藏AGN颜色范围很广，只有部分显示出类似LRD的颜色。 在$z > 6$，这些样本中发现的大多数未隐藏AGN都是LRD，但这可能与这些源具有较大的全波段亮度有关。 由于LRD在星系颜色空间中占据独特位置，它们更容易被瞄准，因此在许多光谱巡天中，没有LRD颜色和斜率的大量宽线AGN代表性不足，因为它们更难预先筛选。 目前的LRD选择技术返回了一个庞大且多样化的人口，包括许多受个体滤光片中发射线流量增强影响的具有$2-5\mu$m颜色的源。 显示英文摘要

摘要： Recently, a large number of compact sources at $z > 4$ with blue UV slopes and extremely red rest-frame optical slopes have been found in James Webb Space Telescope (JWST) extragalactic surveys. As a subsample of these sources, commonly called ``little red dots'' (LRDs), have been spectroscopically observed to host a broad-line active galactic nucleus (AGN), they have been the focus of multiple recent studies in an attempt to understand the origin of their UV and optical emission. Here, we assemble a sample of 123 LRDs from the literature along with spectroscopic and photometric JWST-identified samples of AGNs to compare their colors and spectral slopes. We find that while obscured AGNs at $z < 6$ have highly dissimilar colors to LRDs, unobscured AGNs at $z < 6$ span a wide range of colors, with only a subsample showing colors similar to LRDs. At $z > 6$, the majority of the unobscured AGNs that have been found in these samples are LRDs, but this may be related to the fact that these sources are at large bolometric luminosities. Because LRDs occupy a unique position in galaxy color space, they are more straightforward to target, and the large number of broad-line AGNs that do not have LRD colors and slopes are therefore underrepresented in many spectroscopic surveys because they are more difficult to pre-select. Current LRD selection techniques return a large and disparate population, including many sources having $2-5\mu$m colors impacted by emission line flux boosting in individual filters.