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arXiv 1806.02547gr-qcastro-ph.HE
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脉冲星绕超大质量黑洞运行时的传播延迟

The propagation delay in the timing of a pulsar orbiting a supermassive black hole

Eva Hackmann, Arnab Dhani

摘要:

观测到一颗脉冲星紧密地围绕着银河系中心的超大质量黑洞运行,将为准确确定黑洞参数和对广义相对论进行新的检验打开一扇窗户。在时间模型中必须考虑的一个重要的相对论效应是脉冲在黑洞的引力场中的传播延迟。由于脉冲星和超大质量背洞的极端质量比,我们使用测试粒子的限制,推导出一个精确的解析公式的传播延迟在史瓦西时空。然后,我们比较这一结果的传播延迟在通常采用后牛顿近似,特别是夏皮罗延迟到第二后牛顿秩序。对于边缘上的轨道,我们还考虑修改夏皮罗延迟考虑透镜效应。然后,我们的结果被用来评估的准确性的不同顺序的后牛顿近似的传播延迟。这一比较表明,对于(近)边缘上的轨道,应使用新的精确延迟公式。

英文摘要:

The observation of a pulsar closely orbiting the galactic center supermassive black hole would open the window for an accurate determination of the black hole parameters and for new tests of General Relativity. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay in a Schwarzschild spacetime. We then compare this result to the propagation delays derived in the usually employed post-Newtonian approximation, in particular to the Shapiro delay up to the second post-Newtonian order. For edge-on orbits we also consider modifications of the Shapiro delay which take the lensing effects into account. Our results are then used to assess the accuracy of the different orders of the post-Newtonian approximation of the propagation delay. This comparison indicates that for (nearly) edge-on orbits the new exact delay formula should be used.

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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