Rotating Charged Black Holes with Scalar Hair Constructed via the Newman-Janis Algorithm: Accretion Disk Structure and Shadow Characteristics
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2025
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| author | Cai, Ziqiang Ban, Zhenglong Liang, Qi-Qi Feng, Haiyuan Long, Zheng-Wen |
| author_facet | Cai, Ziqiang Ban, Zhenglong Liang, Qi-Qi Feng, Haiyuan Long, Zheng-Wen |
| contents | In this paper, we generate a rotating charged black hole (BH) with scalar hair via the Newman--Janis algorithm (NJA) and study its thin accretion disk and shadow. The structure of the event horizon and ergosurface is analyzed in detail, revealing how the charge parameter $Q$ and scalar hair parameter $s$ influence the spacetime geometry. We analyze the energy flux and temperature distribution of the accretion disk, finding that increasing either $Q$ or $s$ leads to higher energy flux and peak temperature. The BH shadow is also examined, showing that its apparent size decreases monotonically with increasing $Q$ or $s$. Notably, in the near-extremal regime, the shadow develops a distinctive cuspy edge, indicative of strong light bending in the scalarized and charged spacetime. By comparing the theoretically predicted shadow diameter with Event Horizon Telescope (EHT) observations of Sgr A$^*$, we derive observational constraints on the model parameters. For inclination angles of $17^\circ$ and $90^\circ$, a joint analysis constrains the charge parameter to $0<Q<0.522745$ (at fixed $s=0.1$) and the scalar hair parameter to $0<s<0.283373$ (at fixed $Q=0.3$). Our results demonstrate how scalar hair and electric charge leave imprints on accretion disk emissions and black hole shadows, offering new observational signatures for testing gravity theories beyond general relativity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_01226 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Rotating Charged Black Holes with Scalar Hair Constructed via the Newman-Janis Algorithm: Accretion Disk Structure and Shadow Characteristics Cai, Ziqiang Ban, Zhenglong Liang, Qi-Qi Feng, Haiyuan Long, Zheng-Wen General Relativity and Quantum Cosmology In this paper, we generate a rotating charged black hole (BH) with scalar hair via the Newman--Janis algorithm (NJA) and study its thin accretion disk and shadow. The structure of the event horizon and ergosurface is analyzed in detail, revealing how the charge parameter $Q$ and scalar hair parameter $s$ influence the spacetime geometry. We analyze the energy flux and temperature distribution of the accretion disk, finding that increasing either $Q$ or $s$ leads to higher energy flux and peak temperature. The BH shadow is also examined, showing that its apparent size decreases monotonically with increasing $Q$ or $s$. Notably, in the near-extremal regime, the shadow develops a distinctive cuspy edge, indicative of strong light bending in the scalarized and charged spacetime. By comparing the theoretically predicted shadow diameter with Event Horizon Telescope (EHT) observations of Sgr A$^*$, we derive observational constraints on the model parameters. For inclination angles of $17^\circ$ and $90^\circ$, a joint analysis constrains the charge parameter to $0<Q<0.522745$ (at fixed $s=0.1$) and the scalar hair parameter to $0<s<0.283373$ (at fixed $Q=0.3$). Our results demonstrate how scalar hair and electric charge leave imprints on accretion disk emissions and black hole shadows, offering new observational signatures for testing gravity theories beyond general relativity. |
| title | Rotating Charged Black Holes with Scalar Hair Constructed via the Newman-Janis Algorithm: Accretion Disk Structure and Shadow Characteristics |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2509.01226 |