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arXiv 1409.0159astro-ph.HE
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年轻脉冲星风终端激波处的超高能cosmic ray加速

On ultra-high energy cosmic ray acceleration at the termination shock of young pulsar winds

Martin Lemoine, Kumiko Kotera, Jérôme Pétri

摘要:

脉冲星风星云(PWNe)是自然界中杰出的加速器,因为它们将电子加速到辐射反应极限。受此观察的启发,本文探讨了年轻的脉冲星风星云在脉冲星风的终止激波处将离子加速到超高能量的可能性。我们在这里考虑强大的PWNe,由出生时具有$\sim\,$毫秒周期的光子提供能量。假设这样的质子星存在,至少在中子星诞生后的几年内,并且它们将离子注入风中,我们发现,对于基准旋转周期$P\,\sim\,1\,$ msec和脉冲星磁场$B_{\star}\,\sim\,10^{13}\,$ G,质子可以被加速到Greisen-Zatsepin-Kuzmin截止量级的能量,这意味着基准风光度$L_{\rm p}\,\sim\,10^{45}\,$ erg/s和自旋下降时间$t_{\rm sd}\,\sim 3\times 10^7\,$ s。主要的限制因素是由星云中的同步加速器损失和终止激波的大小决定的;因此,具有$Z\geq 1$的离子可能会被加速到更高的能量。我们推导出一个由源区相互作用产生的相关中微子通量。对于质子占主导地位的组合物,我们的最大通量略低于IceCube-86的5年灵敏度,高于Askaryan射电阵列的3年灵敏度。因此,它可能在未来十年内被探测到,这取决于这些毫秒脉冲星风星云对超高能宇宙射线通量的确切贡献水平。

英文摘要:

Pulsar wind nebulae (PWNe) are outstanding accelerators in Nature, in the sense that they accelerate electrons up to the radiation reaction limit. Motivated by this observation, this paper examines the possibility that young pulsar wind nebulae can accelerate ions to ultra-high energies at the termination shock of the pulsar wind. We consider here powerful PWNe, fed by pulsars born with $\sim\,$millisecond periods. Assuming that such pulsars exist, at least during a few years after the birth of the neutron star, and that they inject ions into the wind, we find that protons could be accelerated up to energies of the order of the Greisen-Zatsepin-Kuzmin cut-off, for a fiducial rotation period $P\,\sim\,1\,$msec and a pulsar magnetic field $B_{\star}\,\sim\,10^{13}\,$G, implying a fiducial wind luminosity $L_{\rm p}\,\sim\,10^{45}\,$erg/s and a spin-down time $t_{\rm sd}\,\sim 3\times 10^7\,$s. The main limiting factor is set by synchrotron losses in the nebula and by the size of the termination shock; ions with $Z\geq 1$ may therefore be accelerated to even higher energies. We derive an associated neutrino flux produced by interactions in the source region. For a proton-dominated composition, our maximum flux lies slightly below the 5-year sensitivity of IceCube-86 and above the 3-year sensitivity of the projected Askaryan Radio Array. It might thus become detectable in the next decade, depending on the exact level of contribution of these millisecond pulsar wind nebulae to the ultra-high energy cosmic ray flux.

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