2020 Fiscal Year Annual Research Report
Using nebular spectra to reveal the progenitor and explosion mechanism of core-collpase supernovae
| Project/Area Number |
20J23342
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| Research Institution | Kyoto University |
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Principal Investigator |
方 其亮 京都大学, 理学研究科, 特別研究員(DC1)
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| Project Period (FY) |
2020-04-24 – 2023-03-31
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| Keywords | Supernvoa / Transient source / Spectrum |
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| Outline of Annual Research Achievements |
We present an analysis of the nebular spectra of 103 stripped-envelope (SE) supernovae (SN). The line profile and width of [O I] are employed to infer the ejecta geometry and the expansion velocity of the inner core, which are then compared with the SN subtypes and [O I]/[Ca II] ratio (an indicator of the progenitor CO core mass).
Based on the best-fit results of the [O I] profile, we conclude that the deviation from spherical symmetry is a common feature for all types of SESNe.
A correlation between [O I] width and [O I]/[Ca II] is discerned, indicating that the oxygen-rich material tends to expand faster for objects with a more massive CO core. Such a correlation can be utilized to constrain the relation between the progenitor mass and the kinetic energy of the explosion.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The main purpose of this project is to reveal the explosion mechanism of core-collapse supernova (CCSN). To understand the explosion mechanism, there are two factors must be clarified, i.e., how much energy is released during the explosion, and how the energy is distributed. The total amount of energy determines the expansion velocity of the ejecta, which affects the width of the emission lines emerged in the nebular spectrum.
We have confirmed that the line width is positive correlated with the mass of the progenitor. More massive star will tend to release more energy during the explosion. Based on the results of hydrodynamic simulations, we derive the quantitative relation between the progenitor mass and energy, which is crucial to understanding the explosion mechanism.
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| Strategy for Future Research Activity |
In the current work, we have derived the relation between the progenitor mass and the released energy. However, knowing how much energy is released is not enough to reveal the explosion mechanism. How the energy is distributed is also important, which will affect the geometry of the ejecta, and further determines the profile of the emission lines emerged in the nebular spectrum.
In the future work, we will focus on the statistical analysis of the line profile of SESN. We have already confirmed the deviation from spherical symmetry is a common feature base on the analysis of oxygen line. We will further extend the analysis to the calcium line, which traces the configuration of the explosion region. The geometry of the ejecta will put further constrain on the explosion mechanism.
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Research Products
(3 results)
