Abstract
In this paper, we investigate the effect of higher curvature corrections from Gauss–Bonnet gravity on the shadow of charged black holes in both AdS and Minkowski spacetimes. The null geodesic equations are computed in d=5 spacetime dimensions by using the directions of symmetries and Hamilton–Jacobi equation. With the null geodesics in hand, we then proceed to evaluate the celestial coordinates (alpha , beta ) and the radius R_s of the black hole shadow and represent it graphically. The effects of charge Q of the black hole and the Gauss–Bonnet parameter gamma on the radius of the shadow R_s is studied in detail. It is observed that the Gauss–Bonnet parameter gamma affects the radius of the black hole shadow R_s differently for the AdS black hole spacetime in comparison to the black hole spacetime which is asymptotically flat. In particular the radius of the black hole shadow increases with increase in the Gauss–Bonnet parameter in case of the AdS black hole spacetime and decreases in case of the asymptotically flat black hole spacetime. We then introduce a plasma background in order to observe the change in the silhouette of the black hole shadow due to a change in the refractive index of the plasma medium. Finally, we study the effect of the Gauss–Bonnet parameter gamma on the energy emission rate of the black hole which depends on the black hole shadow radius and represent the results graphically.
Highlights
Primarily the interest lies in studying black hole shadows, yet there has been study of shadows even for wormholes [20] and intense research is going on in this area in the hope of getting some possible observable predictions.The concept of working with higher curvature gravity has been of great interest recently due to its occurrence in the effective low energy action of superstring theories
We observe from the figures that in case of the Ad S black hole spacetime (l = 1), an increase in the value of the GB parameter γ enlarges the size of the black hole shadow
In this paper we investigate the shadow of charged Gauss–Bonnet black holes for an infinitely distant observer in d = 5 spacetime dimensions
Summary
Primarily the interest lies in studying black hole shadows, yet there has been study of shadows even for wormholes [20] and intense research is going on in this area in the hope of getting some possible observable predictions. In a recent paper [21], the structure of black hole shadows were investigated in (4 + 1) dimensions in the context of holography. Such studies provide a good motivation to look at black hole shadows for Gauss–Bonnet black holes in 5-dimensions. Shadow in case of Gauss–Bonnet gravity has been studied in [22,23] considering spin and in higher dimensions. Our work investigates the shadow of charged Gauss–Bonnet gravity in d = 5-dimensions without spin for asymptotically AdS and Minkowski spaces. We look at the black hole shadow of these black holes in a plasma medium and investigate the effects of various parameters on the shadow radius.
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