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arXiv 0708.1970astro-ph
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在低和高红移的对创造超新星

Pair creation supernovae at low and high redshift

N. Langer, C. A. Norman, A. de Koter, Jorick Vink, M. Cantiello, S. -C. Yoon

摘要:

成对产生超新星(PCSN)被认为是由非常大质量的低金属量恒星产生的。异常明亮的SN 2006 gy确实显示了PCSNe的预期特征。在这里,我们调查的金属阈值低于PCSN可以形成和估计其发生率。对150 $\mso$和250 $\mso$的低金属丰度恒星(Z $_{\odot}$ /5和Z $_{\odot}$ /20)进行了恒星演化计算,并分析了它们的质量损失率。我们发现,准化学均匀演化的快速旋转和传统的演化较慢的旋转,这已经发现大规模的低金属丰度恒星,在这里考虑的质量范围内的分歧。因此,有两种不同的PCSN祖先类型:(I)快速旋转体从非常大质量的沃尔夫-拉叶星中产生PCSN,(II)慢速旋转体在富含氢的大质量黄超巨星中产生PCSN。我们发现,富含氢的PCSN可能发生在金属丰度高达Z $_{\odot}$ /3,这-假设标准IMF仍然有效,以估计其出生率-结果约为一个PCSN每1000超新星在本地宇宙,和一个PCSN每100超新星在红移$z=5$。WC型沃尔夫-拉叶星的PCSNe仅限于低得多的金属丰度。

英文摘要:

Pair creation supernovae (PCSN) are thought to be produced from very massive low metallicity stars. The spectacularly bright SN 2006gy does show signatures expected from PCSNe. Here, we investigate the metallicity threshold below which PCSN can form and estimate their occurrence rate. We perform stellar evolution calculations for stars of 150$\mso$ and 250$\mso$ of low metallicity (Z$_{\odot}$/5 and Z$_{\odot}$/20), and analyze their mass loss rates. We find that the bifurcation between quasi-chemically homogeneous evolution for fast rotation and conventional evolution for slower rotation, which has been found earlier for massive low metallicity stars, persists in the mass range considered here. Consequently, there are two separate PCSN progenitor types: (I) Fast rotators produce PCSNe from very massive Wolf-Rayet stars, and (II) Slower rotators that generate PCSNe in hydrogen-rich massive yellow hypergiants. We find that hydrogen-rich PCSNe could occur at metallicities as high as Z$_{\odot}$/3, which -- assuming standard IMFs are still valid to estimate their birth rates -- results in a rate of about one PCSN per 1000 supernovae in the local universe, and one PCSN per 100 supernovae at a redshift of $z=5$. PCSNe from WC-type Wolf-Rayet stars are restricted to much lower metallicity.

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