Numerically Modeling the First Peak of the Type IIb SN 2016gkg
Numerically Modeling the First Peak of the Type IIb SN 2016gkg
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DOI：
10.3847/1538-4357/aa8595
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
A. Piro;M. Muhleisen;I. Arcavi;D. Sand;L. Tartaglia;S. Valenti
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作者：
A. Piro;M. Muhleisen;I. Arcavi;D. Sand;L. Tartaglia;S. Valenti
许多IIb型超新星（SNe）在其光变曲线中显示出一个突出的额外早期峰值，这通常被认为是由于爆炸星星氦核周围的富氢物质的冲击冷却。最近的SN 2016 gkg是在爆炸后不久发现的IIb型SN，这使其成为研究第一个峰值的绝佳候选者。我们用数值方法分解了一个扩展包络模型的大网格，并将其与SN 2016 gkg进行了比较，以研究从其光变曲线中可以得出哪些约束。这包括探索对流包络线和光学厚稳态风的密度分布，后者通常没有被认为是IIb型SNe模型。我们发现，大致的扩展材料的半径再现光度光变曲线数据，与爆炸前的成像一致。这些值与该材料的假定密度分布无关，尽管对流分布提供了更好的拟合。我们从我们的模型中推断，爆炸必须发生在第一个观测数据点的102 -3小时内，这表明该事件是在非常接近爆炸的时刻发生的。然而，我们最好的拟合一维模型高估了最早的速度测量，这表明富氢物质不是以球对称的方式分布的。我们比较这一点的不对称性，也已经看到在SN IIb残留的Cas A，我们讨论了IIb型SN祖细胞和爆炸模型的影响。
Many Type IIb supernovae (SNe) show a prominent additional early peak in their light curves, which is generally thought to be due to the shock cooling of extended hydrogen-rich material surrounding the helium core of the exploding star. The recent SN 2016gkg was a nearby Type IIb SN discovered shortly after explosion, which makes it an excellent candidate for studying this first peak. We numerically explode a large grid of extended envelope models and compare these to SN 2016gkg to investigate what constraints can be derived from its light curve. This includes exploring density profiles for both a convective envelope and an optically thick steady-state wind, the latter of which has not typically been considered for Type IIb SNe models. We find that roughly of extended material with a radius of reproduces the photometric light curve data, consistent with pre-explosion imaging. These values are independent of the assumed density profile of this material, although a convective profile provides a somewhat better fit. We infer from our modeling that the explosion must have occurred within ≈2–3 hr of the first observed data point, demonstrating that this event was caught very close to the moment of explosion. Nevertheless, our best-fitting 1D models overpredict the earliest velocity measurements, which suggests that the hydrogen-rich material is not distributed in a spherically symmetric manner. We compare this to the asymmetries that have also been seen in the SN IIb remnant Cas A, and we discuss the implications of this for Type IIb SN progenitors and explosion models.