Tidal disruption of stars by supermassive black holes at the centers of galaxies is expected to produce unique emission line signatures, which have not yet been explored adequately. Here we report the discovery of extremely strong coronal lines from [Fe X] up to [Fe XIV] in a sample of seven galaxies (including two recently reported cases), that we interpret as such signatures. This is the first systematic search for objects of this kind, by making use of the immense database of the Sloan Digital Sky Survey. The galaxies, which are non-active as evidenced by the narrow-line ratios, show broad emission lines of complex profiles in more than half of the sample. Both the high ionization coronal lines and the broad lines turn out to be fading on time scales of years in objects observed with spectroscopic follow-ups, suggesting their transient nature. Variations of inferred non-stellar continua, which have absolute magnitudes of at least -16 to -18 mag in the g band, are also detected in more than half of the sample. These extreme coronal line emitters reside in sub-L_* disk galaxies (-21.3 < M_i < -18.5) with small stellar velocity dispersions. The sample seems to form two distinct types based on the presence or absence of the [Fe VII] lines, with the latter having relatively low luminosities of [O III], [Fe XI], and the host galaxies. These characteristics can most naturally be understood in the context of transient accretion onto intermediate mass black holes at galactic centers following tidal disruption of stars in a gas-rich environment. We estimate the incidence of such events to be around 10^-5 per year for a galaxy with -21.5 < M_i < -18.5.
Temporal Variation of the Coronal Radius Parameter in a Jetted Tidal Disruption Event: Swift J1644+57
University of Manitoba（曼尼托巴大学）；Chungbuk National University（忠北国立大学）；Aoyama Gakuin University（青山学院大学）；Physical Research Laboratory（物理研究实验室）；Indian Centre for Space Physics（印度空间物理中心）；Indian Institute of Astrophysics（印度天体物理研究所）；INAF-IASF Palermo（意大利国家天体物理研究所巴勒莫天体物理研究所）；University of British Columbia（不列颠哥伦比亚大学）；SRM University-AP（SRM大学安得拉邦校区）
AT 2018dyk: tidal disruption event or active galactic nucleus? Follow-up observations of an extreme coronal line emitter with the Dark Energy Spectroscopic Instrument
通过暗能量光谱仪后续观测和宿主星系分析，确认 AT 2018dyk 是发生在富气体环境中的潮汐瓦解事件，并发现此类 TDE 的中红外特性与局部环境物质含量及密度相关。
VLASS tidal disruption events with optical flares II: discovery of two TDEs with intermediate width Balmer emission lines and connections to the ambiguous extreme coronal line emitters
Discovery of Quasi-periodic Eruptions in the Tidal Disruption Event and Extreme Coronal Line Emitter AT2022upj: implications for the QPE/TDE fraction and a connection to ECLEs
Early results in the search for extreme coronal line emitters with the Dark Energy Spectroscopic Instrument
University of Southampton（南安普顿大学）；Institute of Cosmology and Gravitation, University of Portsmouth（朴茨茅斯宇宙学与引力研究所）；American Museum of Natural History（美国自然历史博物馆）；University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）；University of Rochester（罗切斯特大学）
NTT, Spitzer and Chandra spectroscopy of SDSSJ095209.56+214313.3: the most luminous coronal-line supernova ever observed, or a stellar tidal disruption event ?
The Radio Properties of Extreme Coronal Line Emitters: Constraints on the Sub-parsec Environment
University of Arizona（亚利桑那大学）；University of Utah（犹他大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；University of California, Berkeley（加利福尼亚大学伯克利分校）；Stanford University（斯坦福大学）
Probing the statistical correlation of optical tidal disruption events with high-energy neutrinos
Institute of Astrophysics, FORTH（FORTH天体物理研究所）；Department of Physics, University of Crete（克里特大学物理系）；Institutt for Fysikk, Norwegian University of Science and Technology（挪威科技大学物理系）；Finnish Centre for Astronomy with ESO (FINCA)（芬兰ESO天文中心（FINCA））；Aalto University Metsähovi Radio Observatory（阿尔托大学梅塔霍维射电天文台）
ATLAS22kjn (AT 2022fpx): A Coronal Line Emitter with an Early Light Curve Bump and Mid-Infrared Dust Echo
University of Illinois（伊利诺伊大学）；Institute for Astronomy, University of Hawai‘i（夏威夷大学天文研究所）；School of Physics, University of Melbourne（墨尔本大学物理学院）；The Ohio State University（俄亥俄州立大学）；Texas Tech University（德克萨斯理工大学）；Peking University（北京大学）；National Astronomical Observatories, Chinese Academy of Science（中国科学院国家天文台）
Discovery of crested quasi-periodic eruptions following the most luminous SRG/eROSITA tidal disruption event
Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Excellence Cluster ORIGINS（ORIGINS 卓越集群）；School of Physics and Astronomy, Tel Aviv University（特拉维夫大学物理与天文学学院）；Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（麻省理工学院卡弗里天体物理学与空间研究研究所）；Centro de Astrobiologia (CAB), CSIC-INTA（CSIC-INTA 天体生物学中心）；European Southern Observatory（欧洲南方天文台）
Rapid onset of a Comptonisation zone in the repeating tidal disruption event XMMSL2 J140446.9-251135
Telespazio UK for ESA（ESA英国泰莱斯帕齐奥）；Schmidt Sciences（施密特科学）；Space Telescope Science Institute（太空望远镜科学研究所）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；University of Arizona（亚利桑那大学）；Max-Planck-Institut für extraterrestrische Physik（马普地外物理研究所）；University of Hertfordshire（赫特福德大学）；University of Oxford（牛津大学）；Centro de Astrobiología (CAB), CSIC-INTA（CSIC-INTA天体生物学中心）；ESA（欧洲空间局）；SERCO for ESA（ESA塞科服务）
eROSITA-RU Tidal Disruption Events with Keck-I/LRIS: Sample Selection, Optical Properties, and Host Galaxy Demographics
University of California, Berkeley（加州大学伯克利分校）；Sichuan University（四川大学）；Miller Institute for Basic Research in Science（米勒基础科学研究学院）；Berkeley Center for Multi-messenger Research on Astrophysical Transients and Outreach (Multi-RAPTOR)（伯克利多信使天体物理瞬变现象研究与外展中心（Multi-RAPTOR））；Space Research Institute (IKI), Russian Academy of Sciences（俄罗斯科学院空间研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
High-ionization coronal lines trace quasar-like activity in recently quenched galaxies at high redshift
Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间科学部）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；INAF – Astronomical Observatory of Trieste（意大利国家天体物理研究所的里雅斯特天文台）；IFPU – Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）
UGC 2369S: a Kpc Scale Triple Merger Candidate Identified in a Nearby Luminous Infrared Galaxy
California Institute of Technology（加州理工学院）；Eureka Scientific（尤里卡科学）；University of California, Berkeley（加利福尼亚大学伯克利分校）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；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）
Kazan (Volga Region) Federal University（喀山（伏尔加沿岸）联邦大学）；Tatarstan Academy of Sciences（鞑靼斯坦科学院）；Space Research Institute, Russian Academy of Sciences（俄罗斯科学院空间研究所）；Max Planck Institute for Astrophysics（马克斯·普朗克天体物理研究所）
X-ray and optical decline of the intermediate mass black hole HLX-1
INAF-Osservatorio Astrofisico di Torino（意大利国家天体物理研究所都灵天文台）；College of Astronomy and Space Sciences, University of the Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；Sydney Institute for Astronomy, School of Physics A28, The, University of Sydney（悉尼大学物理学院天体物理研究所）；INAF-Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所天文与行星物理学研究所）；Dipartimento di Fisica, Universitá degli Studi di Torino（都灵大学物理系）；Dipartimento di Fisica, Universitá di Roma Tor Vergata（罗马第二大学物理系）；Istituto Nazionale di Fisica Nucleare, Sezione di Torino（意大利国家核物理研究所都灵分部）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理与超级计算中心）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）
