2020/04/30 by Shafqat Ul Islam, Rahul Kumar, Sushant G. Ghosh
Physics and Astronomy · #gr-qc
paper · pdf · doi:10.1088/1475-7516/2020/09/030
published as JCAP 09, 030 (2020) · 14 pages, 6 figures, and 2 tables. Matched with the published version
arxiv created 2020/09/16 · arxiv updated 2020/09/17
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 \citeGlavan:2019inb, 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 a and b, 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.