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Published August 2016 | Version Published
Journal Article Open

iPTF15dtg: a double-peaked Type Ic supernova from a massive progenitor

Creators

  • 1. ROR icon Stockholm University
  • 2. ROR icon Texas Tech University
  • 3. ROR icon Weizmann Institute of Science
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon Jet Propulsion Lab
  • 6. ROR icon Los Alamos National Laboratory

Abstract

Context. Type Ic supernovae (SNe Ic) arise from the core-collapse of H- (and He-) poor stars, which could either be single Wolf-Rayet (WR) stars or lower-mass stars stripped of their envelope by a companion. Their light curves are radioactively powered and usually show a fast rise to peak (~10−15 d), without any early (in the first few days) emission bumps (with the exception of broad-lined SNe Ic) as sometimes seen for other types of stripped-envelope SNe (e.g., Type IIb SN 1993J and Type Ib SN 2008D). Aims. We have studied iPTF15dtg, a spectroscopically normal SN Ic with an early excess in the optical light curves followed by a long (~30 d) rise to the main peak. It is the first spectroscopically-normal double-peaked SN Ic to be observed. Our aim is to determine the properties of this explosion and of its progenitor star. Methods. Optical photometry and spectroscopy of iPTF15dtg was obtained with multiple telescopes. The resulting light curves and spectral sequence are analyzed and modeled with hydrodynamical and analytical models, with particular focus on the early emission. Results. iPTF15dtg is a slow rising SN Ic, similar to SN 2011bm. Hydrodynamical modeling of the bolometric properties reveals a large ejecta mass (~10 M_⊙) and strong ^(56)Ni mixing. The luminous early emission can be reproduced if we account for the presence of an extended (≳500 R_⊙), low-mass (≳0.045 M_⊙) envelope around the progenitor star. Alternative scenarios for the early peak, such as the interaction with a companion, a shock-breakout (SBO) cooling tail from the progenitor surface, or a magnetar-driven SBO are not favored. Conclusions. The large ejecta mass and the presence of H- and He-free extended material around the star suggest that the progenitor of iPTF15dtg was a massive (≳35 M_⊙) WR star that experienced strong mass loss.

Additional Information

© 2016 ESO. Received: 13 April 2016. Accepted: 31 May 2016. We gratefully acknowledge the support from the Knut and Alice Wallenberg Foundation. 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. This paper made use of Lowell Observatory's Discovery Channel Telescope (DCT). Lowell operates the DCT in partnership with Boston University, Northern Arizona University, the University of Maryland, and the University of Toledo. Partial support of the DCT was provided by Discovery Communications. The Large Monolithic Imager (LMI) on DCT was built by Lowell Observatory using funds from the National Science Foundation (AST-1005313). LANL participation in iPTF was funded by the US Department of Energy as part of the Laboratory Directed Research and Development program. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We thank N. Blagorodnova, E. Bellm, Y. Cao, G. Duggan, S. Kulkarni, J. Jencson, P. Nugent, for their precious help with the observations of iPTF15dtg and contribution to iPTF. We thank L. Yan for her comments on the paper. 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. A. Corsi acknowledges support from NSF CAREER Award #1455090.

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Additional details

Identifiers

Eprint ID
72121
Resolver ID
CaltechAUTHORS:20161117-112958640

Funding

Knut and Alice Wallenberg Foundation
Discovery Communications
NSF
AST-1005313
Department of Energy (DOE)
NASA/JPL/Caltech
NSF
AST-1455090

Dates

Created
2016-11-17
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Updated
2021-11-11
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Caltech groups
Palomar Transient Factory, Infrared Processing and Analysis Center (IPAC)