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arXiv 2001.09385astro-ph.HE
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双星系统中黑洞周围的引力弹弓

Gravitational slingshots around black holes in a binary

Fan Zhang

摘要:

测试质量体绕天体(散射中心)进行引力弹弓的速度增益随着天体的速度和紧凑性而增加(质量体的轨迹可能发生更大的偏转,而不会击中物体的表面)。紧双星(由两个黑洞组成;我们不考虑X射线双星)中的黑洞(BH)本身以相对论速度运动,代表最佳散射中心。因此,一个吸积物质粒子的子群,被卷入BH双星周围的混沌轨道,可能会反复地被弹弓击中,并被加速到超相对论速度(如地球上的观察者所看到的),最终逃离双星,以及被BH吞噬的命运。逃逸的粒子可以在地球上以超高能宇宙射线(UHECR)的形式被观测到。研究这种可能性需要广义相对论的弹弓公式,因为涉及的速度很高,而且与黑洞的距离很近。我们在本文中推导出它们,并表明粒子的洛伦兹因子中的每一个弹弓的百分比增益即使在粒子被激发时也保持不变,从而证明弹弓机制原则上可以将粒子加速到极端能量。

英文摘要:

The speed gain of a test mass from taking a gravitational slingshot around a celestial object (scattering centre) increases with the latter's speed and compactness (stronger deflection of the mass' trajectory becomes possible without it hitting the surface of the object). The black holes (BHs) in a tight binary (consisting of two black holes; we are not considering X-ray binaries), themselves moving at relativistic speeds, represent optimal scattering centres. Therefore, a sub-population of accreting matter particles, swept up into chaotic orbits around a BH binary, might repeatedly take slingshots and become accelerated to ultra-relativistic speeds (as seen by observers on Earth), ultimately escaping from the binary, as well as the fate of being devoured by a BH. The escaped particles can plausibly be observed on Earth as ultra-high-energy cosmic rays (UHECRs). Investigating such a possibility would require general relativistic slingshot formulae due to the high speeds involved and the close encounters with BHs. We derive them in this paper, and show that the percentage gain per slingshot in a particle's Lorentz factor remains undiminished even as the particle energizes up, thus demonstrating that the slingshot mechanism can in principal accelerate particles to extreme energies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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