Gravitational lensing by black holes in the 4D Einstein-Gauss-Bonnet gravity

Abstract

Recently, a non-trivial 4D Einstein-Gauss-Bonnet (EGB) theory of gravity, by rescaling the GB coupling parameter as α/(D−4), was formulated in [1], which bypasses Lovelock's theorem and avoids Ostrogradsky instability. The theory admits a static spherically symmetric black hole, unlike 5D EGB or general relativity counterpart, which can have both Cauchy and event horizons. We generalize previous work, on gravitational lensing by a Schwarzschild black hole, in the strong and weak deflection limits to the 4D EGB black holes to calculate the deflection coefficients ā and b̄, while former increases and later decrease with increasing α. We also find that the deflection angle αD, angular position θ∞ and um decreases, but angular separation s increases with α. The effect of the GB coupling parameter α on positions and magnification of the source relativistic images is discussed in the context of SgrA* and M87* black holes. A brief description of the weak gravitational lensing using the Gauss-Bonnet theorem is presented.

Holographic superconductors in 4D Einstein-Gauss-Bonnet gravity

“…Interestingly, the solution of the same form has been presented in the conformal anomaly inspired gravity [40,41]. Along this line, the Einstein-Gauss-Bonnet gravity in the 4D spacetime has been explored extensively on various aspects, including the exact solutions [42][43][44][45][46][47][48][49][50][51][52][53][54][55], the quasinormal modes and stability [56][57][58][59][60][61][62][63][64][65][66][67], the observable shadows [68][69][70][71][72][73], the geodesics and gravitational lensing [74][75][76][77][78], and the thermodynamics and cosmic censorship conjecture [79][80][81][82][83][84][85][86].…”

Born–Infeld black holes in 4D Einstein–Gauss–Bonnet gravity

“…The temperature vanishes for the extremal black hole, which can be easily proved with the critical condition (22). In the large β and small α limits, the temperature reduces to…”

Tidal effects in 4D Einstein–Gauss–Bonnet black hole spacetime

“…The physical properties and the novel observable a e-mail: csb3752@hunnu.edu.cn (corresponding author) b e-mail: jljing@hunnu.edu.cn effects for these black hole solutions have been explored in Refs. [2][3][4][5][6][7]. However, there are also some criticisms on this theory of Gravity [8][9][10][11][12].…”