Work

Probing the scalar hair of rotating Horndeski black holes through thick disk images

Year: 2026

Type: article

Abstract: Horizon-scale images of black holes provide a potential probe of fundamental physics, including tests of gravity and black-hole hair. To assess the impact of scalar hair on accretion-flow imaging self-consistently, we construct an analytical model of a geometrically thick, magnetized disk around a rotating hairy black hole in Horndeski theory and analyze its 230 GHz image morphology. We find that scalar hair modestly alters the inflow and magnetic-field structure but strengthens gravitational redshift, markedly reducing the total flux and lensed ring brightness through relativistic transfer and spectral-shift effects. Moreover, we identify a novel, spatially resolved imaging feature: the maximum interferometric diameter of the first photon ring responds strongly to the hair parameter but shows little dependence on accretion-flow details, making it a promising observable for constraining black-hole hair with future space-based interferometry.

Source: Physical review. D/Physical review. D.

DOI: 10.1103/zjtb-3dyz

Authors: Qian Wan, Yehui Hou, Minyong Guo

Institutions: South China University of Technology, Shanghai Jiao Tong University, Beijing Normal University

Language: English

Topic: Astrophysical Phenomena and Observations

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Natural Science Foundation of China, Beijing Normal University

Awards: G1404181171, G3606435161, G4270005851