The fast, luminous ultraviolet transient AT2018cow: extreme supernova, or disruption of a star by an intermediate-mass black hole?

Perley, Daniel A ; Mazzali, Paolo A ; Yan, Lin ; Cenko, S Bradley ; Gezari, Suvi ; Taggart, Kirsty ; Blagorodnova, Nadia ; Fremling, Christoffer ; Mockler, Brenna ; Singh, Avinash ; Tominaga, Nozomu ; Tanaka, Masaomi ; Watson, Alan M ; Ahumada, Tomás ; Anupama, G C ; Ashall, Chris ; Becerra, Rosa L ; Bersier, David ; Bhalerao, Varun ; Bloom, Joshua S ; Butler, Nathaniel R ; Copperwheat, Chris ; Coughlin, Michael W ; De, Kishalay ; Drake, Andrew J ; Duev, Dmitry A ; Frederick, Sara ; González, J Jesús ; Goobar, Ariel ; Heida, Marianne ; Ho, Anna Y Q ; Horst, John ; Hung, Tiara ; Itoh, Ryosuke ; Jencson, Jacob E ; Kasliwal, Mansi M ; Kawai, Nobuyuki ; Khanam, Tanazza ; Kulkarni, Shrinivas R ; Kumar, Brajesh ; Kumar, Harsh ; Kutyrev, Alexander S ; Lee, William H ; Maeda, Keiichi ; Mahabal, Ashish ; Murata, Katsuhiro L ; Neill, James D ; Ngeow, Chow-Choong ; Penprase, Bryan ; Pian, Elena ; Quimby, Robert ; Ramirez-Ruiz, Enrico ; Richer, Michael G ; Román-Zúñiga, Carlos G ; Sahu, D K ; Srivastav, Shubham ; Socia, Quentin ; Sollerman, Jesper ; Tachibana, Yutaro ; Taddia, Francesco ; Tinyanont, Samaporn ; Troja, Eleonora ; Ward, Charlotte ; Wee, Jerrick ; Yu, Po-Chieh (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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Official URL: http://doi.org/10.1093/mnras/sty3420

Related URL: http://dx.doi.org/10.1093/mnras/sty3420

Abstract

Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −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 detailed investigation of their properties. We present photometry and spectroscopy from a comprehensive worldwide campaign to observe AT 2018cow (ATLAS 18qqn), 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 and 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 < 1014 cm after 1 month). This behaviour 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
Source:Copyright of this article belongs to The Royal Astronomical Society
Keywords:Black hole, stars, supernovae: general, supernova: individual: AT2018cow
ID Code:130610
Deposited On:01 Dec 2022 11:07
Last Modified:01 Dec 2022 11:07

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