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arXiv · 2506.13504

Lorentz violation signatures in the low-energy sector of Hořava 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 Hořava 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 Hořava 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 Hořava gravity from black hole shadow observations. https://doi.org/10.1016/j.physletb.2025.139812

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