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arXiv 1302.4482astro-ph.HE
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河外脉冲星的超高能Cosmic Ray核及其银河系对应物的效应

Ultrahigh Energy Cosmic Ray Nuclei from Extragalactic Pulsars and the effect of their Galactic counterparts

Ke Fang, Kumiko Kotera, Angela V. Olinto

摘要:

在快速旋转的新生恒星中,高能核的加速可以解释观测到的高能宇宙射线的光谱,以及俄歇天文台报告的能量高于$10^{19}\,$ eV的重核趋势。脉冲星加速意味着由于脉冲星自旋下降导致的硬注入谱($\sim E^{-1}$)和由于中子星自旋速率的限制导致的最大能量$E_{\rm max} \sim Z \, 10^{19}$ eV。我们以前已经表明,通过年轻的超新星遗迹逃逸软化了光谱,稍微降低了最大能量,并产生次级核。在这里,我们表明,脉冲星的出生周期的分布和传播的影响,在星际和星系间的媒体修改的组合频谱的所有脉冲星。通过假设脉冲星诞生周期的正态分布为中心在300毫秒,我们表明,河外脉冲星诞生的贡献的高能宇宙射线谱自然会引起非常高的能量宇宙射线(VHECR,之间的$10^{16}$和$10^{18}$ eV)的银河系脉冲星诞生的贡献。所需的注入成分,以适应观察到的光谱取决于绝对能量尺度,这是不确定的,不同的俄歇天文台和望远镜阵列。银河系脉冲星诞生的贡献也可以弥合超新星遗迹中宇宙射线加速预测与脚踝以下观测光谱之间的差距,这取决于逃离超新星遗迹的宇宙射线的成分和银河系中VHECR的扩散行为。

英文摘要:

The acceleration of ultrahigh energy nuclei in fast spinning newborn pulsars can explain the observed spectrum of ultrahigh energy cosmic rays and the trend towards heavier nuclei for energies above $10^{19}\,$eV as reported by the Auger Observatory. Pulsar acceleration implies a hard injection spectrum ($\sim E^{-1}$) due to pulsar spin down and a maximum energy $E_{\rm max} \sim Z \, 10^{19}$ eV due to the limit on the spin rate of neutron stars. We have previously shown that the escape through the young supernova remnant softens the spectrum, decreases slightly the maximum energy, and generates secondary nuclei. Here we show that the distribution of pulsar birth periods and the effect of propagation in the interstellar and intergalactic media modifies the combined spectrum of all pulsars. By assuming a normal distribution of pulsar birth periods centered at 300 ms, we show that the contribution of extragalactic pulsar births to the ultrahigh energy cosmic ray spectrum naturally gives rise to a contribution to very high energy cosmic rays (VHECRs, between $10^{16}$ and $10^{18}$ eV) by Galactic pulsar births. The required injected composition to fit the observed spectrum depends on the absolute energy scale, which is uncertain, differing between Auger Observatory and Telescope Array. The contribution of Galactic pulsar births can also bridge the gap between predictions for cosmic ray acceleration in supernova remnants and the observed spectrum just below the ankle, depending on the composition of the cosmic rays that escape the supernova remnant and the diffusion behavior of VHECRs in the Galaxy.

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