https://doi.org/10.1140/epjp/s13360-025-07039-9
Regular Article
The image of scalar hairy black holes with asymmetric potential
1
School of Aeronautics and Astronautics, Shanghai Jiao Tong University, 200240, Shanghai, People’s Republic of China
2
School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang, 200240, Shanghai, People’s Republic of China
3
Shanghai Frontiers Science Center of Gravitational Wave Detection, 800 Dongchuan Road, Minhang, 200240, Shanghai, People’s Republic of China
4
Facultad de Ciencias, Observatorio Astronómico Nacional, Universidad Nacional de Colombia, Sede Bogotá, Ciudad Universitaria, 111321, Bogotá, Colombia
a
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Received:
30
July
2024
Accepted:
6
November
2025
Published online:
4
March
2026
Abstract
Black hole accretion disks are a fascinating topic in astrophysics, as they play a crucial role in several high-energy situations. This paper investigates the optical appearance of scalar hairy black holes (SHBHs) with asymmetric potential, a numerical solution obtained in Phys. Rev. D 68, 044006 (2003). Since the solution is spherically symmetric and surrounded by a thin accretion disk, we base our analysis on the work of J. P. Lumininet (1979). We discuss the behavior of the effective potential for massive and massless particles, the innermost stable circular orbits (ISCO), and the photon sphere radius for different SHBHs. The study includes the plots of isoradial curves and spectral shifts arising from gravitational and Doppler shifts by considering direct and secondary images. Based on the work of Page and Thorne (1974), we also investigate the intrinsic intensity of radiation emitted by the disk at a given radius, which allows the calculation of the distribution of observed bolometric flux. We use the angular size of the shadow reported by the EHT for Sagittarius A* and M87* to constrain the SHBHs parameters.
© The Author(s) 2026
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