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arXiv · 2506.13504

Lorentz violation signatures in the low-energy sector of Ho\v{r}ava gravity from black hole shadow observations

Wentao Liu·Hongxia Huang·Di Wu·Jieci Wang
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Abstract

In this paper, we use the Ho\v{r}ava gravity model and EHT observations of supermassive black holes (BHs) to investigate signatures of Lorentz violation in real astrophysical environments. The Lorentz violation in the rotating Ho\v{r}ava BH spacetime are confined to the strong gravitational field region, being induced by the BH's rotation. Due to the non-separability of the photon motion equations in this spacetime, we employed a numerical backward ray-tracing method to generate shadow images for various BH parameters. Subsequently, we extracted coordinate positions characterizing the shadow shape from high-pixel images to evaluate the parameter space of the BH. When evaluating M87*, Lorentz violation can occur with arbitrary strength. However, for Sgr A*, we can impose certain parameter constraints on Lorentz violation. These constraints depend on the BH's spin. If future observations confirm Sgr A*'s spin parameter less than 0.81 at maximum inclination, current EHT results would challenge general relativity and support Lorentz violation in low-energy regimes.

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Wentao Liu, Hongxia Huang, Di Wu, Jieci Wang. 2025-06-16. Lorentz violation signatures in the low-energy sector of Ho\v{r}ava gravity from black hole shadow observations. https://doi.org/10.1016/j.physletb.2025.139812

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