The majority of most luminous quasars during the epoch of reionization accrete near or above the Eddington limit, marking the vigorous growth of primitive supermassive black holes (SMBHs). However, their subsequent evolution and environmental impact remain poorly characterized. We present JWST/NIRSpec prism IFU observations of HSC J2239+0207, a low-luminosity quasar at $z\sim6.25$ likely in a late stage of mass assembly with an overmassive SMBH relative to its host galaxy. Using H$β$ and H$α$ broad emission lines, we estimate an SMBH mass $M_{\rm BH}\sim3\times10^8~M_{\odot}$ and confirm its sub-Eddington accretion at $λ_{\rm Edd}\sim0.4$. Strong FeII emission and a proximity zone of typical size suggest a metal-rich, highly evolved system. In the far-UV, this quasar presents strong broad-absorption-line features, indicative of high-velocity winds ($ν\sim10^4~{\rm km/s}$). Meanwhile, minimal dust reddening is inferred from the quasar continuum and broad-line Balmer decrement, suggesting little dust along the polar direction. Most interestingly, we identify a gas companion $\sim$5 kpc from the quasar with a high [OIII]/H$β$ ratio ($\gtrsim10$), likely representing outflowing gas blown away by AGN feedback. These results highlight HSC J2239+0207 as a likely fading quasar in transition, providing rare insights into SMBH evolution, AGN feedback, and AGN-galaxy interactions in the early Universe.
Black Hole Feedback, Galaxy Quenching and Outflows at Cosmic Dawn: Analysis of the SEEDZ Simulations
Maynooth University（梅努斯大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；University of Cambridge（剑桥大学）；Universität Heidelberg（海德堡大学）；Georgia Institute of Technology（佐治亚理工学院）；University College Cork（科克大学学院）；Cardiff University（卡迪夫大学）；University of Edinburgh（爱丁堡大学）
Gravitational Waves from Cosmic Dawn: Tracing Cosmic Black Hole Binaries with ET, LGWA, and LISA
INAF/Osservatorio Astronomico di Roma（罗马天文台）；INFN, Sezione Roma1（罗马第一分部意大利国家核物理研究所）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天体物理研究所）；Sapienza School for Advanced Studies（萨皮恩扎高等研究学院）
Lyman-alpha Radiation Pressure in Dense Star Clusters: Implications for Star Formation and Winds at Cosmic Dawn
Center for Computational Astrophysics, Flatiron Institute（平顿研究所计算天体物理中心）；Department of Physics and Astronomy, Rutgers University（罗格斯大学物理与天文系）；Department of Physics, The University of Texas at Dallas（德克萨斯大学达拉斯分校物理系）
Discovery of Quasar Variability and Early Accretion Disk Signatures at Cosmic Dawn
Massachusetts Institute of Technology（麻省理工学院）；Columbia University（哥伦比亚大学）；Flatiron Institute（平顿研究所）；University of Portsmouth（朴茨茅斯大学）；University of Arizona（亚利桑那大学）；University of Michigan（密歇根大学）
The case for super-Eddington accretion in JWST broad-line AGN during the first billion years
NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；Space Telescope Science Institute（空间望远镜科学研究所）；Space Telescope Science Institute for the European Space Agency (ESA)（欧洲空间局空间望远镜科学研究所）；The William H. Miller III Department of Physics and Astronomy, Johns Hopkins University（约翰霍普金斯大学威廉H·米勒三世物理与天文学系）；Department of Astronomy, University of Washington（华盛顿大学天文学系）；Department of Astronomy, University of Texas at Austin（得克萨斯大学奥斯汀分校天文学系）
Beyond the Monsters: A More Complete Census of Black Hole Activity at Cosmic Dawn
Providence College（普罗维登斯学院）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；University of Connecticut（康涅狄格大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；University of Massachusetts Amherst（马萨诸塞大学阿默斯特分校）；Space Telescope Science Institute（空间望远镜科学研究所）；Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；University of Louisville（路易斯维尔大学）；Rochester Institute of Technology（罗切斯特理工学院）；Colby College（科尔比学院）；Harvard University（哈佛大学）；University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Beijing Normal University（北京师范大学）
Extreme Enrichment at Cosmic Dawn: Three FeII-Strong Quasars at z > 6 from the JWST Aether survey
NSF NOIRLab, Gemini Observatory（美国国家光学红外天文实验室，双子座天文台）；International Gemini Observatory/NSF NOIRLab（国际双子座天文台/美国国家光学红外天文实验室）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Institute for Theoretical Physics, Heidelberg University（海德堡大学理论物理研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所天文与空间科学观测站）；Dipartimento di Fisica Enrico Fermi, Università di Pisa（比萨大学恩里科·费米物理系）
A New Sample of $\sim$ 100 Intermediate-mass Black Holes Reaching $z \approx 1$
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Key Laboratory for Polar Science, Ministry of Natural Resources, Polar Research Institute of China（自然资源部极地科学重点实验室，中国极地研究中心）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Department of Astronomy, University of Science and Technology of China（中国科学技术大学天文学系）；Polar Research Institute of China（中国极地研究中心）
