Letter

A likely decade-long sustained tidal disruption event

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Abstract

Multiwavelength flares from tidal disruption and accretion of stars can be used to find and study otherwise dormant massive black holes in galactic nuclei 1 . Previous well-monitored candidate flares were short-lived, with most emission confined to within 1 year 2,​3,​4,​5 . Here we report the discovery of a well-observed super-long (>11 years) luminous X-ray flare from the nuclear region of a dwarf starburst galaxy. After an apparently fast rise within 4 months a decade ago, the X-ray luminosity, though showing a weak trend of decay, has been persistently high at around the Eddington limit (when the radiation pressure balances the gravitational force). The X-ray spectra are soft — steeply declining towards higher energies — and can be described with Comptonized emission from an optically thick low-temperature corona, a super-Eddington accretion signature often observed in accreting stellar-mass black holes 6 . Dramatic spectral softening was also caught in one recent observation, implying either a temporary transition from the super-Eddington accretion state to the standard thermal state, or the presence of a transient highly blueshifted (0.36c) warm absorber. All these properties in concert suggest a tidal disruption event with an unusually long super-Eddington accretion phase that has never before been observed.

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Author information

Affiliations

  1. Space Science Center, University of New Hampshire, Durham, New Hampshire 03824, USA

    • Dacheng Lin
  2. Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, Massachusetts 02138, USA

    • James Guillochon
  3. QianNan Normal University for Nationalities, Longshan Street, Duyun City of Guizhou Province, China

    • S. Komossa
  4. Department of Astronomy and Astrophysics, University of California, Santa Cruz, California 95064, USA

    • Enrico Ramirez-Ruiz
  5. Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, Alabama 35487, USA

    • Jimmy A. Irwin
  6. Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea

    • Jimmy A. Irwin
  7. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts 02138, USA

    • W. Peter Maksym
  8. Space Science Center, Morehead State University, 235 Martindale Drive, Morehead, Kentucky 40351, USA

    • Dirk Grupe
  9. CNRS, IRAP, 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France

    • Olivier Godet
    • , Natalie A. Webb
    •  & Didier Barret
  10. Université de Toulouse, UPS-OMP, IRAP, Toulouse, France

    • Olivier Godet
    • , Natalie A. Webb
    •  & Didier Barret
  11. Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, New York 10003 USA

    • B. Ashley Zauderer
  12. AIM Paris-Saclay Service d'Astrophysique, CEA-Saclay, 91191 Gif sur Yvette, France

    • Pierre-Alain Duc
  13. Gemini Observatory/AURA, Southern Operations Center, Casilla 603, La Serena, Chile

    • Eleazar R. Carrasco
  14. Canadian Astronomy Data Centre, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7, Canada

    • Stephen D. J. Gwyn

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Contributions

D.L. wrote the main manuscript and led the data analysis. J.G. helped with the modelling of the long-term X-ray light curve and wrote the text on the modelling in the Supplementary Information. S.G. stacked the CFHT images. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Dacheng Lin.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    Supplementary Notes 1–13, Supplementary Tables 1–2, Supplementary Figures 1–8, Supplementary References.