Analytical Kerr-Sen dilaton-axion black hole lensing in the weak deflection limit

Abstract

We investigate analytically gravitational lensing by charged, stationary, axially symmetric Kerr-Sen dilaton-axion black hole in the weak deflection limit. Approximate solutions to the lightlike equations of motion are present up to and including third-order terms in M/b, a/b and r α /b, where M is the black hole mass, a is the angular momentum, r α = Q 2 /M , Q being the charge and b is the impact parameter of the light ray. We compute the positions of the two weak field images, the corresponding signed and absolute magnifications up to post-Newtonian order. It is shown that there are static post-Newtonian corrections to the signed magnification and their sum as well as to the critical curves, which are functions of the charge. The shift of the critical curves as a function of the lens angular momentum is found, and it is shown that they decrease slightly with the increase of the charge. The point-like caustics drift away from the optical axis and do not depend on the charge. All of the lensing quantities are compared to particular cases as Schwarzschild and Kerr black holes as well as the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole.

Gravitational lensing by black holes

“…These studies allow to get interesting analytical approximations in some limits that we will sometimes recall later. Lensing by rotating black holes in some alternative theories of gravity has also been explored [80][81][82].…”

Particles collision near Kerr–Sen Dilaton-Axion black hole

“…Thermodynamic and astrophysical consequences of the Sen black hole have been studied by several authors [43,44,45,46,47,48,49,50,51]. Here we consider static, axially symmetric, rotating and charged Kerr-Sen Dilaton-Axion black hole metric in generalized Boyer-Lindquist coordinates given by [37]…”

“…So, sometimes it is called twisted Kerr black hole or Kerr-Sen black hole. In Kerr-Sen black hole, the thermodynamic properties are discussed in [39,40] and analytical gravitational lensing are discussed in [37,41]. Hidden symmetries, null geodesics and photon capture in the Sen black hole have been studied in [42].…”

“…Till now, several authors [19,20,21,22,23,24,25,26,27,28,29,30,31,32,34,35,36] have studied the CM energy of the collision of particles near the horizons of black holes. Our main motivation is to investigate the geodesic study of the static, axially symmetric, rotating and charged Kerr-Sen Dilaton-Axion black hole [37]. The CM energy and the particles orbit are investigated for two colliding neutral particles of different rest masses falling from infinity to near the event horizon, Cauchy horizon and extremal horizon of Kerr-Sen Dilaton-Axion black hole.…”

Semiclassical gravitational effects on the gravitational lensing in the spacetime of topological defects

“…Mellier [34] had studied most of these recent works regarding on WGL and discuss their impact for cosmology. This led some authors to consider the WGL for studying black holes [35][36][37]. The GL has also of theoretical importance, from a strong field perspective.…”