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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. . (Unpublished)

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The discovery of SN 2018gep (ZTF18abukavn) 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-supernova 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 ∼2M⊙, explosion energy ∼10⁵² erg, a circumstellar medium of mass ∼0.3M⊙ and radius ∼1000R⊙, and a ⁵⁶Ni mass of ∼0.3M⊙ 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:Report or Paper (Discussion Paper)
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:We thank Jared Goldberg, David Khatami, 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 JF acknowledges 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 and JP20K04024.
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
Subject Keywords:Supernovae (1668) – Supernova dynamics (1664) – Concept: Radiative transfer – Concept: Light curves – Stellar pulsations (1625)
Record Number:CaltechAUTHORS:20210408-151804427
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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:09 Apr 2021 18:36

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