发表机构
INAF – Osservatorio Astronomico di Roma; Scuola Normale Superiore; NSF’s National Optical-Infrared Astronomy Research Laboratory; Department of Astronomy, The University of Texas at Austin; Cosmic Frontier Center, The University of Texas at Austin; Armagh Observatory and Planetarium; Institute for Astronomy, University of Edinburgh; Astrophysics Science Division, NASA Goddard Space Flight Center; Center for Space Sciences and Technology, UMBC（意大利国家天体物理研究所罗马天文台; 比萨高等师范学院; 美国国家光学红外天文研究实验室; 德克萨斯大学奥斯汀分校天文学系; 德克萨斯大学奥斯汀分校宇宙前沿中心; 阿马赫天文馆与天文台; 爱丁堡大学天体物理研究所; NASA戈达德太空飞行中心天体物理学部; 马里兰大学巴尔的摩分校空间科学与技术中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用JWST/NIRSpec数据，发现CANDELS天区中LAE比例随红移演化，揭示星系演化与再电离共同影响Lyα可见度，支持渐进式再电离历史。
AI 中文摘要
我们利用公开的詹姆斯·韦伯空间望远镜近红外光谱仪（JWST/NIRSpec）棱镜光谱数据，在五个CANDELS天区中研究了莱曼α（Lyα）可见度的演化以及莱曼α发射体（LAE）的物理性质。我们的星表包含3446个经光谱确认、红移范围为4 ≤ z < 14.2的源，其中3361个为恒星形成星系（SFG），在这些SFG中，539个是可靠的（信噪比S/N > 3）LAE。我们测量了等效宽度EW₀ > 25埃的LAE所占比例（记为X_Lyα），并在两个紫外光度区间（分别为-20.25 < M_UV < -18.75和-21.75 < M_UV < -20.25）追踪其红移演化。在较暗的紫外光度区间内，X_Lyα从红移z=5到z=6以3σ显著性水平上升，随后在更高红移处下降，且在z > 6时呈现出显著的单调下降趋势。我们还研究了LAE和全部SFG样本的物理性质，发现LAE的恒星质量、紫外斜率β、恒星红化程度、恒星形成率（SFR）、金属丰度、比恒星形成率（sSFR）以及爆发性均随红移保持大致稳定，唯一例外是质量加权年龄，其随红移增加而减小。相反，全部SFG样本的性质随红移发生显著演化，且随着红移增加，SFG的性质逐渐趋近于LAE所在的星系性质空间区域。这表明，星系演化可能在更早的宇宙时期增强了Lyα光子的本征产生与逃逸。我们认为，在从观测到的Lyα发射可见度推断星系际介质（IGM）的中性氢含量演化时，必须考虑这一效应。为此，我们采用了基于无衰减模型（Attenuation-Free Model）的物理动机框架，联合考虑星系演化与IGM衰减的共同作用。我们的观测结果支持再电离历史以渐进方式进行，而非宇宙中性氢分数快速增加的情景。
英文摘要
We investigate the evolution of Ly$α$ visibility and the physical properties of Ly$α$ emitters (LAEs) across the five CANDELS fields using publicly available JWST/NIRSpec PRISM spectroscopy. Our catalog comprises 3446 spectroscopically confirmed sources at 4 $\leq $ z < 14.2, including 3361 star-forming galaxies (SFGs), of which 539 are robust (S/N > 3) LAEs. We measure the fraction of LAEs with EW$_0$ > 25A (X$_{\mathrm{Lyα}}$) and trace its redshift evolution in two UV luminosity bins, namely -20.25 < M$_{\mathrm{UV}}$ < -18.75 and -21.75 < M$_{\mathrm{UV}}$ < -20.25. Within the fainter-UV range, X$_{\mathrm{Lyα}}$ increases from z = 5 to z = 6 at 3$σ$ significance and subsequently declines toward higher redshifts with a significant monotonic trend at z > 6. We also investigate the physical properties of both LAEs and the full SFG population. We find that the stellar mass, UV slope $β$, stellar reddening, SFR, metallicity, sSFR, and burstiness of LAEs remain approximately stable with redshift. The only exception is the mass-weighted age which decreases with increased redshift. Conversely, the properties of the full SFG population evolve significantly, progressively approaching the region of galaxy-property space occupied by LAEs as redshift increases. This suggests that galaxy evolution may enhance the intrinsic production and escape of Ly$α$ photons toward earlier epochs. We argue that this effect should be accounted when inferring the evolution of the neutral hydrogen content of the IGM from the observed visibility of Ly$α$ emission. To this end, we employ a physically motivated framework based on the Attenuation-Free Model, jointly accounting for galaxy evolution and IGM attenuation. Our observations favor reionization histories that proceed gradually over scenarios characterized by a rapid increase in the cosmic neutral hydrogen fraction.
Comments18 pages, 8 figures, 2 tables. Submitted to the A&A journal. Comments are welcome
