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arXiv 1401.2895astro-ph.SR
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Ia型超新星速率的理论不确定性

Theoretical uncertainties of the type Ia supernova rate

J. S. W. Claeys, O. R. Pols, R. G. Izzard, J. Vink, F. W. M. Verbunt

摘要:

Ia型超新星(SNe Ia)被认为是碳氧白矮星(CO WD)的爆炸。两个主要的演化通道提出的WD达到热核爆炸所需的临界密度:单简并的情况下(SD),其中一个CO WD从一个非简并的同伴,和双简并的情况下(DD),其中两个CO WD合并。然而,在这两种情况下,仍然很难重现观测到的超新星Ia速率。与二进制人口合成代码,我们研究的主要进化渠道,导致超新星Ia和我们计算的超新星Ia率和相关的延迟时间分布。我们发现,DD通道是最长的延迟时间的主要形成通道。具有富氦供体的SD通道是在最短延迟时间处的主导通道。我们的标准模型速率比在星系团中观测到的速率低五倍。我们研究了单星和双星演化的病态约束方面以及不确定的初始双星分布对Ia型超新星速率的影响。这些分布,以及氦星演化和共同的信封演化的不确定性,对我们计算的速率有最大的影响。低效的共同包络演变增加了SD爆炸的相对数量,使得对于$α_{\rm ce} = 0.2$来说,它们在SN Ia速率中占据主导地位。我们的最高速率比星系团SN Ia速率低三倍,但与场星系主导样本中确定的速率兼容。如果我们假设无限的吸积到WD上,以最大限度地增加SD爆炸的数量,我们的速率与观测到的星系团速率是相容的。

英文摘要:

It is thought that type Ia supernovae (SNe Ia) are explosions of carbon-oxygen white dwarfs (CO WDs). Two main evolutionary channels are proposed for the WD to reach the critical density required for a thermonuclear explosion: the single degenerate scenario (SD), in which a CO WD accretes from a non-degenerate companion, and the double degenerate scenario (DD), in which two CO WDs merge. However, it remains difficult to reproduce the observed SN Ia rate with these two scenarios. With a binary population synthesis code we study the main evolutionary channels that lead to SNe Ia and we calculate the SN Ia rates and the associated delay time distributions. We find that the DD channel is the dominant formation channel for the longest delay times. The SD channel with helium-rich donors is the dominant channel at the shortest delay times. Our standard model rate is a factor five lower than the observed rate in galaxy clusters. We investigate the influence of ill-constrained aspects of single- and binary-star evolution and uncertain initial binary distributions on the rate of type Ia SNe. These distributions, as well as uncertainties in both helium star evolution and common envelope evolution, have the greatest influence on our calculated rates. Inefficient common envelope evolution increases the relative number of SD explosions such that for $α_{\rm ce} = 0.2$ they dominate the SN Ia rate. Our highest rate is a factor three less than the galaxy-cluster SN Ia rate, but compatible with the rate determined in a field-galaxy dominated sample. If we assume unlimited accretion onto WDs, to maximize the number of SD explosions, our rate is compatible with the observed galaxy-cluster rate.

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