https://doi.org/10.1140/epjc/s10052-023-12231-1
Regular Article - Theoretical Physics
Investigating shadow images and rings of the charged Horndeski black hole illuminated by various thin accretions
1
College of Physics, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China
2
Key Laboratory of Aerospace Information Materials and Physics (NUAA), MIIT, 211106, Nanjing, China
3
State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, 400074, Chongqing, China
4
Department of Mechanics, Chongqing Jiaotong University, 400074, Chongqing, China
Received:
30
August
2023
Accepted:
6
November
2023
Published online:
18
November
2023
In this paper, we investigate the shadows and rings of the charged Horndeski black hole illuminated by accretion flow that is both geometrically and optically thin. We consider two types of accretion models: spherical and thin-disk accretion flow. We find that in both types of models, the size of the charged Horndeski black hole shadow decreases with the increase of the charge, and it decreases more slowly for the Reissner–Nordström (RN) black hole. In the spherical accretion flow model, we find that the increase of the charge of Horndeski black hole brightens the light ring around it, and it brightens more significantly in comparison with RN black hole. Due to the Doppler effect, the charged Horndeski black holes with accretion flow of radial motion have darker shadows than those with the static accretion flow, but the size of the shadow is not affected by accretion flow motion. In the thin disk-shaped accretion flow model, we find that the brightness of the light ring around the charged Horndeski black hole is dominated by the direct emission from the accretion flow, and the contribution from lensed rings is relatively small, and that from the photon rings is negligible. We also find that the ring brightness decreases as the charge of Horndeski black hole increases, and the decrease is more significant than that in the RN black hole case. Moreover, the radiation position of the accretion flow can affect the shadow size and the ring brightness of the charged Horndeski black hole.
© The Author(s) 2023
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