Quasinormal modes and shadows of black holes in infinite derivative theory of gravity

In this work, we studied the quasinormal modes (QNM) and shadow of a Schwarzschild Black hole (BH) with higher-order metric corrections, in the framework of Infinite Derivative theory of Gravity (IDG). We studied the effects on QNMs and shadow of the BH, which arises from the IDG’s corrections to the BH’s metric. We used 6th order Padé averaged WKB approximation method to study the QNMs of the BH perturbed by a scalar field. We analyze the dependence of the amplitude and damping of QNMs with respect to the free parameters. Next, we studied the time evolution of a scalar field around the BH spacetime. The QNMs have been calculated from the time profile of the evolution. Then we studied the shadow of the BH. The variation of the shadow radius due to inclusion of higher-order corrections was studied and the variation of the shadow radius with respect to the free parameters also studied. Furthermore, the dependence of the shadow radius on the mass of the BH is also studied. Finally, we constrained the free parameters associated with the correction terms using the data from the Keck and VLTI observation, and we obtained some bounds on the parameters.