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Fast Blue Optical Transients Due to Circumstellar Interaction and the Mysterious Supernova SN 2018gep

Leung, Shing-Chi and Fuller, Jim and Nomoto, Ken'ichi (2021) Fast Blue Optical Transients Due to Circumstellar Interaction and the Mysterious Supernova SN 2018gep. Astrophysical Journal, 915 (2). Art. No. 80. ISSN 0004-637X. doi:10.3847/1538-4357/abfcbe.

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The discovery of SN 2018gep (ZTF 18abukavn) challenged our understanding of the late-phase evolution of massive stars and their supernovae (SNe). The fast rise in luminosity of this SN (spectroscopically classified as a broad-lined Type Ic SN) indicates that the ejecta interacts with a dense circumstellar medium (CSM), while an additional energy source such as ⁵⁶Ni decay is required to explain the late-time light curve. These features hint at the explosion of a massive star with pre-SN mass loss. In this work, we examine the physical origins of rapidly evolving astrophysical transients like SN 2018gep. We investigate the wave-driven mass-loss mechanism and how it depends on model parameters such as progenitor mass and deposition energy, searching for stellar progenitor models that can reproduce the observational data. A model with an ejecta mass ~2 M⊙, explosion energy ~10⁵² erg, a CSM of mass ~0.3 M⊙ and radius ~1000 R⊙, and a ⁵⁶Ni mass ~0.3 M⊙ provides a good fit to the bolometric light curve. We also examine how interaction-powered light curves depend more generally on these parameters and how ejecta velocities can help break degeneracies. We find both wave-driven mass loss and mass ejection via pulsational pair instability can plausibly create the dense CSM in SN 2018gep, but we favor the latter possibility.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Leung, Shing-Chi0000-0002-4972-3803
Fuller, Jim0000-0002-4544-0750
Nomoto, Ken'ichi0000-0001-9553-0685
Alternate Title:Fast Blue Optical Transients due to Circumstellar Interaction and the Mysterious SN 2018gep
Additional Information:© 2021. The American Astronomical Society. Received 2021 March 10; revised 2021 April 26; accepted 2021 April 27; published 2021 July 8. We thank Jared Goldberg, David Khatami, Maryam Modjaz, and the ZTF theory network for useful discussions that helped inspire and refine this work. S.C.L. thanks the MESA development community for making the code open-sourced and V. Morozova and her collaborators in providing the SNEC code open source. S.C.L. and J.F. acknowledge support by NASA grants HST-AR-15021.001-A and 80NSSC18K1017. K.N. has been supported by the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan, and JSPS KAKENHI grant numbers JP17K05382, JP20K04024, and JP21H04499. Software: MESA (Paxton et al. 2011, 2013, 2015, 2018) version 8118, SNEC (Morozova et al. 2015).
Group:Astronomy Department, TAPIR, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
NASA Hubble FellowshipHST-AR-15021.001-A
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)JP17K05382
Japan Society for the Promotion of Science (JSPS)JP20K04024
Japan Society for the Promotion of Science (JSPS)JP21H04499
Subject Keywords:Supernovae; Supernova dynamics; Stellar pulsations; Radiative transfer; Light curves
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Supernovae (1668); Supernova dynamics (1664); Stellar pulsations (1625); Radiative transfer (1335); Light curves (918)
Record Number:CaltechAUTHORS:20210408-151804427
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Official Citation:Shing-Chi Leung et al 2021 ApJ 915 80
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108665
Deposited By: Tony Diaz
Deposited On:09 Apr 2021 18:36
Last Modified:12 Jul 2021 20:01

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