AI 中文总结
Skyfire项目通过JWST/NIRSpec巡天，在CEERS天区对z>3的宽线AGN候选体开展光谱普查，明确了LRDs宽线探测比例及修订了选择标准，揭示了LRD-LBD的关联。
AI 中文摘要
我们介绍Skyfire项目，这是一项使用G395M中分辨率光栅的JWST/NIRSpec 3期21小时巡天，覆盖扩展格罗斯带的5个指向天区。该巡天旨在对宇宙早期释放科学（CEERS）巡天在z>3处识别的、具有不同静止光学颜色的暗弱宽线活动星系核（AGN）候选体开展系统普查。我们的主要目标包括通过测光选出的小红点（Little Red Dots, LRDs）、蓝色极端发射线星系（extreme emission line galaxies, EELGs）以及X射线探测到的AGN。我们给出了Skyfire观测的178个源的光谱红移，以及红移范围为2.7<z<6.5的34个宽线源的星表。我们的宽线样本包含18个LRDs，这使得CEERS天区内β_opt>-0.02的LRDs的光谱完备性达到73%。我们探讨了测光选出的LRDs中宽发射线的发生率随其静止帧连续谱斜率和观测颜色分布的变化关系，发现LRDs中的宽线探测比例在相对较蓝的静止光学颜色下仍保持较高水平，并平滑延伸至小蓝点（Little Blue Dots, LBDs）占据的更蓝区域，我们讨论了这一发现对LRD-LBD统一模型的启示。我们还发现，在主要依据高等值宽度发射线和致密形态选出的EELGs中，仅有18%（3/17）表现出宽发射线，这表明仅靠这些标准难以有效预测宽线活动。我们提出了一套修订后的LRD选择标准，通过将β_opt下限扩展至-0.52来涵盖更蓝的源。使用这一新阈值，我们发现F444W波段亮于26.5的测光选出的LRDs中，80.9⁺⁴.⁶₋₇.₅%表现出宽发射线，且LRDs占CEERS天区内识别出的全部宽线源的54%。
英文摘要
We present the Skyfire program, a 21-hour Cycle 3 JWST/NIRSpec survey with the G395M medium-resolution grating covering five pointings in the Extended Groth Strip. The survey is designed to carry out a systematic census of faint, broad-line AGN candidates with a range of rest-optical colors identified at z > 3 by the Cosmic Evolution Early Release Science (CEERS) Survey. Our primary targets include photometrically-selected Little Red Dots (LRDs), blue extreme emission line galaxies (EELGs), and X-ray-detected AGN. We present spectroscopic redshifts for 178 sources observed by Skyfire, as well as a catalog of 34 sources with broad emission lines in the redshift range 2.7 < z < 6.5. Our broad-line sample includes 18 LRDs, which brings the spectroscopic completeness of LRDs with $β_{\rm opt}>-0.02$ in the CEERS field to 73%. We explore the prevalence of broad emission lines in photometrically-selected LRDs as a function of their rest-frame continuum slope and observed color distributions. We find the broad-line detection fraction in LRDs remains high at relatively blue rest-optical colors and extends smoothly into the bluer regime occupied by Little Blue Dots (LBDs). We discuss the implications of this finding for LRD-LBD unification scenarios. We also find that only 18% (3/17) of EELGs selected primarily for their high-equivalent-width emission lines and compact morphologies exhibit broad emission lines, suggesting these criteria alone are poor predictors of broad-line activity. We present a revised set of LRD selection criteria that captures bluer sources by extending down to $β_{\rm opt}=-0.52$. Using this new threshold, we find that $80.9^{+4.6}_{-7.5}\%$ of photometrically-selected LRDs brighter than 26.5 in F444W show broad emission lines and that LRDs make up 54% of the overall broad-line population identified in the CEERS field.
Comments20 Pages, 8 Figures, Submitted to ApJ
