Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society We present optical spectroscopic and Swift UVOT/XRT observations of the X-ray and UV/optical bright tidal disruption event (TDE) candidate AT 2018fyk/ASASSN-18ul discovered by ASAS-SN. The Swift lig...
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| Format: | Journal Article |
| Language: | English |
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OXFORD UNIV PRESS
2019
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| Online Access: | http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/80168 |
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| author | Wevers, T. Pasham, D.R. van Velzen, S. Leloudas, G. Schulze, S. Miller-Jones, James Jonker, P.G. Gromadzki, M. Kankare, E. Hodgkin, S.T. Wyrzykowski Kostrzewa-Rutkowska, Z. Moran, S. Berton, M. Maguire, K. Onori, F. Mattila, S. Nicholl, M. |
| author_facet | Wevers, T. Pasham, D.R. van Velzen, S. Leloudas, G. Schulze, S. Miller-Jones, James Jonker, P.G. Gromadzki, M. Kankare, E. Hodgkin, S.T. Wyrzykowski Kostrzewa-Rutkowska, Z. Moran, S. Berton, M. Maguire, K. Onori, F. Mattila, S. Nicholl, M. |
| author_sort | Wevers, T. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society We present optical spectroscopic and Swift UVOT/XRT observations of the X-ray and UV/optical bright tidal disruption event (TDE) candidate AT 2018fyk/ASASSN-18ul discovered by ASAS-SN. The Swift light curve is atypical for a TDE, entering a plateau after ∼40 d of decline from peak. After 80 d the UV/optical light curve breaks again to decline further, while the X-ray emission becomes brighter and harder. In addition to broad H, He, and potentially O/Fe lines, narrow emission lines emerge in the optical spectra during the plateau phase. We identify both high-ionization (O III) and low-ionization (Fe II) lines, which are visible for ∼45 d. We similarly identify Fe II lines in optical spectra of ASASSN-15oi 330 d after discovery, indicating that a class of Fe-rich TDEs exists. The spectral similarity between AT 2018fyk, narrow-line Seyfert 1 galaxies, and some extreme coronal line emitters suggests that TDEs are capable of creating similar physical conditions in the nuclei of galaxies. The Fe II lines can be associated with the formation of a compact accretion disc, as the emergence of low-ionization emission lines requires optically thick, high-density gas. Taken together with the plateau in X-ray and UV/optical luminosity this indicates that emission from the central source is efficiently reprocessed into UV/optical wavelengths. Such a two-component light curve is very similar to that seen in the TDE candidate ASASSN-15lh, and is a natural consequence of a relativistic orbital pericentre. |
| first_indexed | 2025-11-14T11:15:06Z |
| format | Journal Article |
| id | curtin-20.500.11937-80168 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:15:06Z |
| publishDate | 2019 |
| publisher | OXFORD UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-801682020-07-29T09:31:38Z Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk Wevers, T. Pasham, D.R. van Velzen, S. Leloudas, G. Schulze, S. Miller-Jones, James Jonker, P.G. Gromadzki, M. Kankare, E. Hodgkin, S.T. Wyrzykowski Kostrzewa-Rutkowska, Z. Moran, S. Berton, M. Maguire, K. Onori, F. Mattila, S. Nicholl, M. Science & Technology Physical Sciences Astronomy & Astrophysics accretion accretion discs black hole physics galaxies: nuclei ultraviolet: galaxies X-rays: galaxies FE-II EMISSION BLACK-HOLE MASSES ACCRETION DISC FOLLOW-UP GALAXIES STELLAR POPULATION STARS LINES SPECTROSCOPY © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society We present optical spectroscopic and Swift UVOT/XRT observations of the X-ray and UV/optical bright tidal disruption event (TDE) candidate AT 2018fyk/ASASSN-18ul discovered by ASAS-SN. The Swift light curve is atypical for a TDE, entering a plateau after ∼40 d of decline from peak. After 80 d the UV/optical light curve breaks again to decline further, while the X-ray emission becomes brighter and harder. In addition to broad H, He, and potentially O/Fe lines, narrow emission lines emerge in the optical spectra during the plateau phase. We identify both high-ionization (O III) and low-ionization (Fe II) lines, which are visible for ∼45 d. We similarly identify Fe II lines in optical spectra of ASASSN-15oi 330 d after discovery, indicating that a class of Fe-rich TDEs exists. The spectral similarity between AT 2018fyk, narrow-line Seyfert 1 galaxies, and some extreme coronal line emitters suggests that TDEs are capable of creating similar physical conditions in the nuclei of galaxies. The Fe II lines can be associated with the formation of a compact accretion disc, as the emergence of low-ionization emission lines requires optically thick, high-density gas. Taken together with the plateau in X-ray and UV/optical luminosity this indicates that emission from the central source is efficiently reprocessed into UV/optical wavelengths. Such a two-component light curve is very similar to that seen in the TDE candidate ASASSN-15lh, and is a natural consequence of a relativistic orbital pericentre. 2019 Journal Article http://hdl.handle.net/20.500.11937/80168 10.1093/mnras/stz1976 English http://purl.org/au-research/grants/arc/FT140101082 OXFORD UNIV PRESS fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics accretion accretion discs black hole physics galaxies: nuclei ultraviolet: galaxies X-rays: galaxies FE-II EMISSION BLACK-HOLE MASSES ACCRETION DISC FOLLOW-UP GALAXIES STELLAR POPULATION STARS LINES SPECTROSCOPY Wevers, T. Pasham, D.R. van Velzen, S. Leloudas, G. Schulze, S. Miller-Jones, James Jonker, P.G. Gromadzki, M. Kankare, E. Hodgkin, S.T. Wyrzykowski Kostrzewa-Rutkowska, Z. Moran, S. Berton, M. Maguire, K. Onori, F. Mattila, S. Nicholl, M. Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title | Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title_full | Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title_fullStr | Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title_full_unstemmed | Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title_short | Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate at 2018fyk |
| title_sort | evidence for rapid disc formation and reprocessing in the x-ray bright tidal disruption event candidate at 2018fyk |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics accretion accretion discs black hole physics galaxies: nuclei ultraviolet: galaxies X-rays: galaxies FE-II EMISSION BLACK-HOLE MASSES ACCRETION DISC FOLLOW-UP GALAXIES STELLAR POPULATION STARS LINES SPECTROSCOPY |
| url | http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/80168 |