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The luminous late-time emission of the type-Ic supernova iPTF15dtg – evidence for powering from a magnetar?

Taddia, F. and Sollerman, J. and Fremling, C. and Karamehmetoglu, E. and Barbarino, C. and Lunnan, R. and West, S. and Gal-Yam, A. (2019) The luminous late-time emission of the type-Ic supernova iPTF15dtg – evidence for powering from a magnetar? Astronomy and Astrophysics, 621 . Art. No. A64. ISSN 0004-6361.

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Context. The transient iPTF15dtg is a type-Ic supernova (SN) showing a broad light curve around maximum light, consistent with massive ejecta if we assume a radioactive-powering scenario. Aims. We aim to study the late-time light curve of iPTF15dtg, which turned out to be extraordinarily luminous for a stripped-envelope (SE) SN, and investigate possible powering mechanisms. Methods. We compare the observed light curves to those of other SE SNe and also to models for the ^(56)Co decay. We analyze and compare the spectra to nebular spectra of other SE SNe. We build a bolometric light curve and fit it with different models, including powering by radioactivity, magnetar powering, and a combination of the two. Results. Between 150 and 750 d post-explosion, the luminosity of iPTF15dtg declined by merely two magnitudes instead of the six magnitudes expected from ^(56)Co decay. This is the first spectroscopically regular SE SN found to show this behavior. The model with both radioactivity and magnetar powering provides the best fit to the light curve and appears to be the most realistic powering mechanism. An alternative mechanism might be circumstellar-medium (CSM) interaction. However, the spectra of iPTF15dtg are very similar to those of other SE SNe, and do not show signs of strong CSM interaction. Conclusions. The object iPTF15dtg is the first spectroscopically regular SE SN whose light curve displays such clear signs of a magnetar contributing to its late-time powering. Given this result, the mass of the ejecta needs to be revised to a lower value, and therefore the progenitor mass could be significantly lower than the previously estimated > 35 M⊙.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Taddia, F.0000-0002-2387-6801
Sollerman, J.0000-0003-1546-6615
Fremling, C.0000-0002-4223-103X
Lunnan, R.0000-0001-9454-4639
Gal-Yam, A.0000-0002-3653-5598
Additional Information:© 2019 ESO. Article published by EDP Sciences. Received 21 June 2018; Accepted 4 November 2018; Published online 09 January 2019. FT and JS gratefully acknowledge support from the Knut and Alice Wallenberg Foundation. JS acknowledges the support of Vetenskapsrådet through VR grants 2012-2265 and 2017-03699. This work is partly based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. This work is partly based on observations made with DOLoRes@TNG. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the intermediate Palomar Transient Factory (iPTF) project, a scientific collaboration among the California Institute of Technology, Los Alamos National Laboratory, the University of Wisconsin, Milwaukee, the Oskar Klein Center, the Weizmann Institute of Science, the TANGO Program of the University System of Taiwan, and the Kavli Institute for the Physics and Mathematics of the Universe.
Group:Palomar Transient Factory
Funding AgencyGrant Number
Knut and Alice Wallenberg FoundationUNSPECIFIED
Subject Keywords:supernovae: individual: SN 2011bm – supernovae: individual: iPTF15dtg – supernovae: individual: SN 2010mb – supernovae: general
Record Number:CaltechAUTHORS:20190124-082804593
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Official Citation:The luminous late-time emission of the type-Ic supernova iPTF15dtg – evidence for powering from a magnetar? F. Taddia, J. Sollerman, C. Fremling, E. Karamehmetoglu, C. Barbarino, R. Lunnan, S. West and A. Gal-Yam. A&A, 621 (2019) A64. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92447
Deposited By: Tony Diaz
Deposited On:24 Jan 2019 17:14
Last Modified:21 May 2019 19:37

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