The effect of scalar hair on the charged black hole with the images from accretions disk

Tao-Tao Sui; Zi-Liang Wang; Wen-Di Guo

doi:10.1140/epjc/s10052-024-12807-5

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 441
https://doi.org/10.1140/epjc/s10052-024-12807-5

Regular Article - Theoretical Physics

The effect of scalar hair on the charged black hole with the images from accretions disk

Tao-Tao Sui¹, Zi-Liang Wang² and Wen-Di Guo³^c

¹ College of Physics, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China
² Department of Physics, School of Science, Jiangsu University of Science and Technology, 212003, Zhenjiang, China
³ Institute of Theoretical Physics and Research Center of Gravitation, Lanzhou University, 730000, Lanzhou, China

^c guowd@lzu.edu.cn

Received: 18 January 2024
Accepted: 12 April 2024
Published online: 29 April 2024

Abstract

In this paper, we investigate the optical properties of a charged black hole with scalar hair (CSH) within the context of four-dimensional Einstein–Maxwell–Dilaton gravity. To achieve this, we consider three distinct toy models of thin accretion disks. The presence of dilaton coupling allows us to express both the solutions of CSH and the Reissner–Nordström (RN) black hole in terms of their mass (M) and charge (Q). Our findings reveal differences in the effective potentials $V_{eff}$ $V_{eff}$ , photon sphere radii $r_{ph}$ $r_{ph}$ , and innermost stable circular orbit $r_{isco}$ $r_{isco}$ between the CSH and RN black hole cases, which become increasingly pronounced as the charge parameter Q increases. However, no noticeable distinctions are observed concerning the critical impact parameter $b_{ph}$ $b_{ph}$ . When the ratio of the photon ring band and the lensed ring band exceeds 0.1, it may suggest the presence of a charged black hole with scalar hair. Furthermore, our results underscore the significant influence of the charge parameter Q on the brightness distributions of the direct, lensed ring, and photon ring for three standard emission functions. These findings emphasize the potential for distinguishing between CSH and RN black holes through an analysis of direct intensity and peak brightness in specific accretion disk models.

© The Author(s) 2024

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.