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arXiv · 2607.18751

Novel extended inner shadow in images of Johannsen-Psaltis black holes with thin accretion disks

Xinyu Wang·Xiaobao Wang·Xin-Yang Wang·Minyong Guo
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Abstract

The Johannsen-Psaltis (JP) metric is constructed by introducing deviation parameters into the Kerr metric. The presence of these deviation parameters provides additional degrees of freedom for testing the extent to which astrophysical black holes are consistent with the Kerr paradigm and for examining the validity of the no-hair theorem. Since black hole imaging provides one of the most direct means of probing the properties of astrophysical black holes, a detailed investigation of the imaging characteristics of JP black holes constitutes a natural first step toward employing the JP metric to explore potential deviations from the Kerr geometry in astrophysical black hole systems. Accordingly, numerical backward ray-tracing simulations are employed to conduct a comprehensive investigation of the image structures, intensity distributions, and redshift-blueshift signatures of JP black holes with both closed and non-closed event horizons. The dependence of these imaging characteristics on the deviation parameter is also investigated systematically. Furthermore, the emergence of an extended inner shadow, distinct from the original inner shadow of the black hole, in images of JP black holes with non-closed event horizons motivated a detailed investigation of its physical formation mechanism using both numerical backward ray-tracing simulations and an approximate analytical framework.

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Xinyu Wang, Xiaobao Wang, Xin-Yang Wang, Minyong Guo. 2026-07-21. Novel extended inner shadow in images of Johannsen-Psaltis black holes with thin accretion disks. https://arxiv.org/abs/2607.18751

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