On null geodesics and shadow of hairy black holes in Einstein-Maxwell-dilaton gravity

The time-like and null-like geodesics around compact objects are some of the best tools to classify and understand the structure of a space-time. In this paper, we study the null geodesics around charged static dilaton black holes in Einstein-Maxwell-dilaton gravity. The physical parameters for non-...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2022-05
Main Authors: Heydari-Fard, Mohaddese, Heydari-Fard, Malihe, Sepangi, Hamid Reza
Format: Article
Language:English
Subjects:
Black holes
Circular orbits
Coupling
Dilatons
Geodesy
Impact analysis
Parameters
Photons
Physical properties
Shadows
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The time-like and null-like geodesics around compact objects are some of the best tools to classify and understand the structure of a space-time. In this paper, we study the null geodesics around charged static dilaton black holes in Einstein-Maxwell-dilaton gravity. The physical parameters for non-radial geodesics including the effective potential, effective force, radius of the photon sphere and impact parameter are obtained and effects of the charge parameter and dilaton coupling constant on these quantities are studied. Possible photon motions for different values of the impact parameter are analyzed and unstable circular orbits and unbounded orbits are plotted. These results are compared to that of the Schwarzschild, Reissner-Nordstrom and Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black holes. Also, we study the shadow cast by a dilaton black hole and investigate how the dilaton coupling affects the size of the black hole shadow. Finally, as an application of null geodesics, we calculate the deflection of light and investigate the effects of the model parameters on the bending angle.
ISSN:2331-8422
DOI:10.48550/arxiv.2110.02713