类91T/99aa型Ia超新星2019vrq，第二部分：有前景标准烛光的三维、非局部热动平衡、低振幅脉动延迟爆燃模型
The 91T/99aa-like Type Ia Supernova 2019vrq, Part II: 3D, Non-LTE, Low-Amplitude, Pulsating Delayed-Detonation Models of a Promising Standard Candle
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中文总结 AI 辅助
本研究通过三维非LTE脉动延迟爆燃模型，成功再现了类91T/99aa型超新星2019vrq的光变曲线和光谱，揭示了其非球对称结构和低偏振特性，为高红移宇宙学标准烛光提供了新见解。
中文摘要 AI 辅助
我们基于光变曲线和分光偏振时间序列，分析了超亮、类91T/99aa型Ia超新星SN 2019vrq。我们采用三维辐射流体动力学、完全非局部热动平衡（non-LTE）模拟，对可能旋转的近钱德拉塞卡质量（M_Ch）白矮星（WD）进行低振幅、径向脉动偏中心延迟爆燃（PDD），以再现光变曲线和光谱。前身星源于一颗太阳金属丰度的7倍太阳质量（7 Mo）主序星。爆炸产生0.86倍太阳质量的56Ni和0.023倍太阳质量的58Ni。后者比类91T/99aa型超新星的“经典”延迟爆燃模型低一个数量级，这一诊断特征可直接用JWST检验。缓慢的爆燃留下一个受束缚的、脉动的白矮星。爆燃在0.8倍太阳质量处触发。光变曲线和光谱要求外层有0.11倍太阳质量的未燃烧物质，其铁丰度为太阳的两倍，这很可能是早期一次失败爆炸的灰烬，并且核统计平衡（NSE）元素存在低水平混合。光谱反映了早期高电离随后复合的过程，光球在最大光度前约一周从中等质量元素层转移到NSE主导层。早期高速（HV）CaII IR3谱线（可能由24,000 km/s处0.01倍太阳质量的非球对称密度壳层产生）源于电离夹层结构，而非丰度上的双重结构。在钙复合后，CaII IR3谱线翼延伸至33,000 km/s，远超高速分量。低偏振源于铁族元素主导的光球中低散射，与非球对称性<20%一致，并导致外层方向光度依赖为10-15%，总弥散为35%。光变曲线形状提供了进一步探测非球对称性的手段，与局部测试的偏振测量限制一致，并对高红移宇宙学具有重要意义。
英文摘要
We analyze the overluminous, 91T/99aa-like Type~Ia SN 2019vrq, based on light curves(LCs) and spectropolarimetric time-series. We employ 3D-radiation-hydrodynamical, full non-LTE simulations of low-amplitude, radially-pulsating-off-center-delayed-detonations(PDD) of a possibly rotating near-M(Ch) mass white dwarf (WD) to reproduce the LCs and spectra. The progenitor originates from a 7 Mo main-sequence star of solar metallicity. The explosion yields 0.86Mo of 56Ni and 0.023Mo of 58Ni. The latter falls a factor of 10 below that of `classical' delayed-detonations for 91T/99aa-like SNe, a diagnostic that is directly testable with JWST. The slow deflagration leaves a bound, pulsating WD. The detonation is triggered at 0.8 Mo. LCs and spectra require an outer 0.11 Mo of unburned material with twice-solar Fe, plausibly the ashes of an earlier, unsuccessful explosion, and low-level mixing of nuclear-statistical-equilibrium(NSE) elements. The spectra reflect early high ionization followed by recombination, with the photosphere shifting from intermediate-mass-element- to NSE-dominated layers about a week before maximum. The early high-velocity (HV) CaII IR3 line (likely produced by an aspherical density shell at 24,000km/s of 0.01 Mo) arises from an ionization sandwich rather than a double structure in abundances. After Ca recombines, the CaII IR3 wing reaches 33,000km/s well beyond the HV component. The low polarization is due to low scattering in an iron-group-dominated photosphere, consistent with asphericities <20% and resulting in a directional luminosity dependence 10-15% from the outer layers, and a dispersion of 35% in total. The LC-shape provides a further probe of asphericity, consistent with the locally tested polarimetry limits and relevant for high-z cosmology.
发表机构
- Florida State University（佛罗里达州立大学）
- Tsinghua University（清华大学）
- University of Texas（德克萨斯大学）
- European Organisation for Astronomical Research in the Southern Hemisphere (ESO)（欧洲南方天文台）
- Texas A&M University（德克萨斯农工大学）
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