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arXiv 0907.3196astro-ph.HE
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白矮星的碰撞作为Ia型超新星的一个新的祖先通道

Collisions of white dwarfs as a new progenitor channel for type Ia supernovae

S. Rosswog, D. Kasen, J. Guillochon, E. Ramirez-Ruiz

摘要:

我们提出了一个系统的数值研究结果的替代祖方案,以产生Ia型超新星爆炸,这是不限于CO白矮星的点火附近的Sirrasekhar质量。在这种情况下,两颗白矮星碰撞引发的热核爆炸。一致的建模的气体动力学连同核反应使用平滑粒子和基于网格的流体动力学代码进行研究的可行性,这种替代祖通道。我们发现冲击波触发的点火和Ni的合成实际上是中等质量白矮星对近距离碰撞的自然结果,我们使用多维辐射转移程序计算了这些事件的出射宽带光变曲线和光谱时间序列。合成光谱和光变曲线比较以及与正常Ia型超新星在类似的B波段下降率,并大致符合菲利普斯关系,虽然观察到由于不对称的喷射碎片的视角有轻微的依赖性。虽然银河系中心和球状星团内的事件发生率被发现太低,无法解释Ia型超新星的大部分人口,但它们可能足够频繁,可以对整体发生率做出高达1%的贡献。尽管这些速率估计仍然存在很大的不确定性,但它们确实表明,致密的恒星系统应该为即将到来的超新星调查提供每年数百次此类碰撞引起的热核爆炸。

英文摘要:

We present the results of a systematic numerical study of an alternative progenitor scenario to produce type Ia supernova explosions, which is not restricted to the ignition of a CO white dwarf near the Chandrasekhar mass. In this scenario, a shock-triggered thermonuclear explosion ensues from the collision of two white dwarfs. Consistent modeling of the gas dynamics together with nuclear reactions using both a smoothed particle and a grid-based hydrodynamics code are performed to study the viability of this alternative progenitor channel. We find that shock-triggered ignition and the synthesis of Ni are in fact a natural outcome for moderately massive white dwarf pairs colliding close to head-on. We use a multi-dimensional radiative transfer code to calculate the emergent broadband light curves and spectral time-series of these events. The synthetic spectra and lightcurves compare well with those of normal type Ia supernovae over a similar B-band decline rate and are broadly consistent with the Phillips relation, although a mild dependence on viewing angle is observed due to the asymmetry of the ejected debris. While event rates within galactic centers and globular clusters are found to be much too low to explain the bulk of the type Ia supernovae population, they may be frequent enough to make as much as a one percent contribution to the overall rate. Although these rate estimates are still subject to substantial uncertainties, they do suggest that dense stellar systems should provide upcoming supernova surveys with hundreds of such collision-induced thermonuclear explosions per year.

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