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Perley, DA, Mazzali, PA, Yan, L, Cenko, SB, Gezari, S, Taggart, K, Blagorodnova, N, Fremling, C, Mockler, B, Singh, A, Tominaga, N, Tanaka, M, Watson, AM, Ahumada, T, Anupama, GC, Ashall, C, Becerra, RL, Bersier, D, Bhalerao, V, Bloom, JS , Butler, NR, Copperwheat, CM, Coughlin, MW, De, K, Drake, AJ, Duev, DA, Frederick, S, González, JJ, Goobar, A, Heida, M, Ho, AYQ, Horst, J, Hung, T, Itoh, R, Jencson, JE, Kasliwal, MM, Kawai, N, Kulkarni, SR, Kumar, B, Kumar, H, Kutyrev, AS, Khanam, T, Lee, WH, Maeda, K, Mahabal, A, Murata, KL, Neill, JD, Ngeow, C-C, Penprase, B, Pian, E, Quimby, R, Ramirez-Ruiz, E, Richer, M, Román-Zúñiga, CG, Srivastava, S, Socia, Q, Sollerman, J, Tachibana, Y, Taddia, F, Tinyanont, K, Troja, E, Ward, C and Wee, J (2018) The Fast, Luminous Ultraviolet Transient AT2018cow: Extreme Supernova, or Disruption of a Star by an Intermediate-Mass Black Hole? Monthly Notices of the Royal Astronomical Society, 484 (1). pp. 1031-1049. ISSN 0035-8711
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Abstract
Wide-field optical surveys have begun to uncover large samples of fast (t_rise < 5d), luminous (M_peak < -18), blue transients. While commonly attributed to the breakout of a supernova shock into a dense wind, the great distances to the transients of this class found so far have hampered a detailed investigation of their properties until now. We present photometry and spectroscopy from a comprehensive worldwide campaign to observe AT2018cow (ATLAS18qqn), the first fast-luminous optical transient to be found in real time at low redshift. Our first spectra (<2 days after discovery) are entirely featureless. A very broad absorption feature suggestive of near-relativistic velocities develops between 3-8 days, then disappears. Broad emission features of H and He develop after >10 days. The spectrum remains extremely hot throughout its evolution, and the photospheric radius contracts with time (receding below R<10^14 cm after 1 month). This behavior does not match that of any known supernova, although a relativistic jet within a fallback supernova could explain some of the observed features. Alternatively, the transient could originate from the disruption of a star by an intermediate-mass black hole, although this would require long-lasting emission of highly super-Eddington thermal radiation. In either case, AT 2018cow suggests that the population of fast luminous transients represents a new class of astrophysical event. Intensive follow-up of this event in its late phases, and of any future events found at comparable distance, will be essential to better constrain their origins.
| Item Type: | Article |
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| Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authros. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
| Uncontrolled Keywords: | astro-ph.HE; astro-ph.HE |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | Oxford University Press |
| Related URLs: | |
| Date Deposited: | 18 Dec 2018 11:21 |
| Last Modified: | 04 Sep 2021 02:31 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/9097 |
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