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arXiv · 2404.14764

The unstable null circular geodesic features the spherically symmetrical asymptotically flat black hole

Yuxuan Shi
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Abstract

We analyse the massless particles orbiting a spherically symmetric, asymptotically flat black hole with a radius equal to the photon sphere and a circular geodesic. Asymptotic observers record the orbital period of the null circular geodesic as the lowest among all possible paths around the compact object. We proceed with the analytical study of massless particle motion to demonstrate the instability of an orbit with null circularity. Furthermore, our results apply to any asymptotically flat and spherically symmetric spacetime.

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Yuxuan Shi. 2024-04-23. The unstable null circular geodesic features the spherically symmetrical asymptotically flat black hole. https://arxiv.org/abs/2404.14764

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