Producing Type Iax supernovae from a specific class of helium-ignited WD explosions
Producing Type Iax supernovae from a specific class of helium-ignited WD explosions
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DOI：
10.1051/0004-6361/201322298
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发表时间：
2013-10
影响因子：
6.5
通讯作者：
Bo Wang;S. Justham;Zhanwen Han
中科院分区：
文献类型：
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作者：
Bo Wang;S. Justham;Zhanwen Han
上下文。最近有人提出，Ia型超新星的一个亚类（Ia型超新星）是足够独特和足够普遍的，可以从Ia型超新星的大部分中单独分类；建议将其命名为lax型超新星（SNe lax），以SN 2002cx命名。然而，他们的祖先仍然不确定。目标。我们研究了如果事件起源于次钱德拉塞卡质量爆炸的一个子集，是否可以理解这类的总体性质。在这个潜在的祖星群中，一颗碳氧白矮星（CO WD）从一颗未简并的氦星积累了一层氦；氦层的点火会导致CO - WD的点火。方法。我们将祖先系统的详细二进制进化计算纳入二进制种群综合模型，以获得这些事件的速率和延迟时间。结果。根据我们的标准模型，预测这些爆炸的银河系事件速率类似于1.5 x 10(-3) yr(-1)，与SNe lax的测量速率非常吻合。此外，预测的延迟时间类似于70 Myr-800 Myr，这与大多数SNe lax是在晚型星系中发现的事实相一致。如果假设爆炸是双重爆炸——遵循当前模型的预期——那么，根据爆炸时CO WD质量，我们也估计了得到的SN亮度的分布（-13大于或类似于M-bol大于或类似于-19等），这可以再现SNe lax的经验多样性。结论。我们推测为什么具有非简并供体恒星的双星可能导致SNe松弛，而具有简并供体的类似系统则不会。我们认为，在通常由非简并供体提供的较低吸积速率下点火所必需的高质量氦层可能是产生SN 2002cx类特征所必需的，甚至可能通过改变CO点火的性质。
Context. It has recently been proposed that one subclass of Type Ia supernovae (SNe Ia) is sufficiently distinct and sufficiently common to be classified separately from the bulk of SNe Ia; the suggested class name is Type lax supernovae (SNe lax), after SN 2002cx. However, their progenitors are still uncertain. Aims. We study whether the population properties of this class might be understood if the events originate from a subset of subChandrasekhar mass explosions. In this potential progenitor population, a carbon-oxygen white dwarf (CO WD) accumulates a helium layer from a non-degenerate helium star; ignition of that helium layer then leads to ignition of the CO WD. Methods. We incorporated detailed binary evolution calculations for the progenitor systems into a binary population synthesis model to obtain rates and delay times for these events. Results. The predicted Galactic event rate of these explosions is similar to 1.5 x 10(-3) yr(-1) according to our standard model, in good agreement with the measured rates of SNe lax. In addition, predicted delay times are similar to 70 Myr-800 Myr, consistent with the fact that most of SNe lax have been discovered in late-type galaxies. If the explosions are assumed to be double detonations -following current model expectations - then, based on the CO WD masses at explosion, we also estimate the distribution of resulting SN brightness (-13 greater than or similar to M-bol greater than or similar to -19 mag), which can reproduce the empirical diversity of SNe lax. Conclusions. We speculate on why binaries with non-degenerate donor stars might lead to SNe lax if similar systems with degenerate donors do not. We suggest that the high mass of the helium layer necessary for ignition at the lower accretion rates typically delivered from non-degenerate donors might be necessary to produce SN 2002cx-like characteristics, perhaps even by changing the nature of the CO ignition.