The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole
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Authors
Leloudas, G
Stone, NC
van Velzen, S
Jonker, PG
Arcavi, I
Fremling, C
Maund, JR
Smartt, SJ
Krìhler, T
Miller-Jones, JCA
Vreeswijk, PM
Gal-Yam, A
Mazzali, PA
De Cia, A
Howell, DA
Inserra, C
Patat, F
de Ugarte Postigo, A
Yaron, O
Ashall, C
Bar, I
Campbell, H
Chen, T-W
Childress, M
Elias-Rosa, N
Harmanen, J
Hosseinzadeh, G
Johansson, J
Kangas, T
Kankare, E
Kim, S
Kuncarayakti, H
Lyman, J
Magee, MR
Maguire, K
Malesani, D
Mattila, S
McCully, CV
Nicholl, M
Prentice, S
Romero-Cañizales, C
Schulze, S
Smith, KW
Sollerman, J
Sullivan, M
Tucker, BE
Valenti, S
Wheeler, JC
Young, DR
Publication Date
2016-12-12Journal Title
Nature Astronomy
ISSN
2397-3366
Publisher
Nature Publishing Group
Volume
1
Issue
1
Number
2
Language
English
Type
Article
This Version
AM
Metadata
Show full item recordCitation
Leloudas, G., Fraser, M., Stone, N., van Velzen, S., Jonker, P., Arcavi, I., Fremling, C., et al. (2016). The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole. Nature Astronomy, 1 (1. 2)https://doi.org/10.1038/s41550-016-0002
Abstract
When a star passes within the tidal radius of a supermassive black hole, it will be torn apart$^1$. For a star with the mass of the Sun ($M_\odot$) and a non-spinning black hole with a mass <10$^8M_\odot$, the tidal radius lies outside the black hole event horizon$^2$ and the disruption results in a luminous flare$^{3–6}$. Here we report observations over a period of ten months of a transient, hitherto interpreted$^7$ as a superluminous supernova$^8$. Our data show that the transient rebrightened substantially in the ultraviolet and that the spectrum went through three different spectroscopic phases without ever becoming nebular. Our observations are more consistent with a tidal disruption event than a superluminous supernova because of the temperature evolution$^6$, the presence of highly ionized CNO gas in the line of sight$^9$ and our improved localization of the transient in the nucleus of a passive galaxy, where the presence of massive stars is highly unlikely$^{10,11}$. While the supermassive black hole has a mass >10$^8M_\odot^{12,13}$, a star with the same mass as the Sun could be disrupted outside the event horizon if the black hole were spinning rapidly$^{14}$. The rapid spin and high black hole mass can explain the high luminosity of this event.
Sponsorship
We acknowledge support from the European Union FP7 programme through the following European Research Council grants: 320360 (M.F., H.C.), 647208 (P.G.J.), 291222 (S.J.S.), 615929 (M.S.). We also acknowledge: Einstein Postdoctoral Fellowship PF5-160145 (N.C.S.), Hubble Postdoctoral Fellowship HST-HF2-51350 (S.v.V.), STFC grants ST/I001123/1 ST/L000709/1 (S.J.S.) and ST/L000679/1 (M.S.), Australian Research Council Future Fellowship FT140101082 (J.C.A.M.-J.), a Royal Society University Research Fellowship (J.R.M.), a Sofja Kovalevskaja Award to P. Schady (T.Kr., T.-W.C.), a Ramón y Cajal fellowship and the Spanish research project AYA 2014-58381 (A.de U.P.), CONICYT-Chile FONDECYT grants 3130488 (S.K.), 3140534 (S.S.), 3140563 (H.K.), 3150238 (C.R.-C.), a PRIN-INAF 2014 project (N.E.-R.), support from IDA (D.M.), an Ernest Rutherford Fellowship (K.M.), CAASTRO project number CE110001020 (B.E.T.), National Science Foundation grant AST 11-09881 and NASA grant HST-AR-13726.02 (J.C.W.). This work used observations from the Las Cumbres Observatory Global Telescope Network (LCOGT) and was based upon work supported by National Science Foundation grant 1313484. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by Commonwealth Scientific and Industrial Research Organisation. This work was based partially on observations collected as part of the Public European Southern Observatory Spectroscopic Survey for Transient Objects Survey (PESSTO) under European Southern Observatory (ESO) programmes 188.D-3003 and 191.D-0935, and on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 095.D-0633.
Funder references
European Research Council (320360)
Identifiers
External DOI: https://doi.org/10.1038/s41550-016-0002
This record's URL: https://www.repository.cam.ac.uk/handle/1810/263527
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