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arXiv 1110.0318astro-ph.HE
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核塌缩超新星中r过程元素的抖动喷注核合成

Nucleosynthesis of r-Process Elements by Jittering Jets in Core-Collapse Supernovae

Oded Papish, Noam Soker

摘要:

我们计算了在核心坍缩超新星(CCSNe)爆炸的抖动喷流模型中形成的热泡内部的核合成过程,发现了几倍于10^-4 M_(\odot)的r过程元素的形成.在抖动喷流模型中,从新形成的中子星周围的随机吸积盘发射的快速喷流在数千公里处受到冲击,形成高温高压气泡。这些气泡合并成一个大气泡,使恒星爆炸。在目前的研究中,我们假设一个球对称的均匀气泡,并跟踪其演变约一秒期间,核反应发生。喷流持续时间约为1秒,速度为v_j=0.5c,总能量为10^51尔格。我们使用喷流的中子浓缩与时间无关,并遵循核反应形成种子核直到$Z \leq 50$,在其上更多的中子将被吸收以形成r过程元素。根据种子核的质量,我们发现理想模型中的r过程元素质量是10^-4 M_ \odot的几倍,这略大于从观测中推导出的值。放松均匀气泡和恒定射流成分的假设的更现实的计算可能会导致与观测一致。

英文摘要:

We calculate the nucleosynthesis inside the hot bubble formed in the jittering-jets model for core collapse supernovae (CCSNe) explosions, and find the formation of several times 10^-4 M_\odot of r-process elements. In the jittering-jets model fast jets launched from a stochastic accretion disk around the newly formed neutron star are shocked at several thousands km, and form hot high-pressure bubbles. These bubbles merge to form a large bubble that explode the star. In the current study we assume a spherically symmetric homogenous bubble, and follow its evolution for about one second during which nuclear reactions take place. The jets last for about one second, their velocity is v_j=0.5c, and their total energy is 10^51 erg. We use jets' neutron enrichment independent on time, and follow the nuclear reactions to the formation of the seed nuclei up to $Z \leq 50$, on which more neutrons will be absorbed to form the r-process elements. Based on the mass of the seed nuclei we find the r-process element mass in our idealized model to be several times 10^-4 M_\odot, which is slightly larger than the value deduced from observations. More realistic calculations that relax the assumptions of a homogenous bubble and constant jets composition might lead to agreement with observations.

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