Effect of electric interaction on the deflection and gravitational lensing in the strong field limit

Shangjie Zhou; Muchun Chen; Junji Jia

doi:10.1140/epjc/s10052-023-12047-z

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 883
https://doi.org/10.1140/epjc/s10052-023-12047-z

Regular Article - Theoretical Physics

Effect of electric interaction on the deflection and gravitational lensing in the strong field limit

Shangjie Zhou¹, Muchun Chen¹ and Junji Jia²^c

¹ School of Physics and Technology, Wuhan University, 430072, Wuhan, China
² Center for Astrophysics and MOE Key Laboratory of Artificial Micro- and Nano-Structures, School of Physics and Technology, Wuhan University, 430072, Wuhan, China

^c junjijia@whu.edu.cn

Received: 3 May 2022
Accepted: 15 September 2023
Published online: 30 September 2023

Abstract

The deflection angle $Δ ϕ$ $\Delta \phi$ of charged signals in general charged spacetime in the strong deflection limit is analyzed in this work using a perturbative method generalized from the neutral signal case. The solved $Δ ϕ$ $\Delta \phi$ naturally contains the finite distance effect and takes a quasi-power series form with a logarithmic divergence at the leading order. The coefficients of the series contain both the gravitational and electric contributions. Using the Reissner–Nordström spacetime as an example, we found that an electric repulsion (or attraction) tends to decrease (or increase) the critical impact parameter $b_{c}$ $$b_c$$ . If the repulsion is strong enough, then $b_{c}$ $$b_c$$ can shrink to zero and the critical particle sphere $r_{0 c}$ $r_{0c}$ will disappear. These results are applied to the gravitational lensing of charge signal, from which we solved the image positions, their magnifications and time delays. It is found that in general, the electric repulsion (or attraction) will decrease (or increase) the image apparent angles, the black hole shadow sizes as well as their magnifications but increase (or decrease) the time delays.

© The Author(s) 2023

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