Shadows of Kerr–Vaidya-like black holes

Abstract

In this work, we study the shadow boundary curves of rotating time-dependent black hole solutions which have well-defined Kerr and Vaidya limits. These solutions are constructed by applying the Newman-Janis algorithm to a spherically symmetric seed metric conformal to the Vaidya solution with a mass function that is linear in Eddington-Finkelstein coordinates. Equipped with a conformal Killing vector field, this class of solution exhibits separability of null geodesics, thus allowing one to develop an analytic formula for the boundary curve of its shadow. We find a simple power law describing the dependence of the mean radius and asymmetry factor of the shadow on the accretion rate. Applicability of our model to recent Event Horizon Telescope observations of M87∗ and Sgr A∗ is also discussed.

Parameter estimation of the Bardeen-Kerr black hole in cloud of strings using shadow analysis

“…Recently, the method of estimating the distortion of black hole shadow from circular shape is proposed by Hioki and Maeda [33] and its generalizations for static [34][35][36][37][38] and rotating black holes are also considered [39][40][41][42][43][44][45][46][47][48][49]. The spatial angular resolution of VLBI radio observation is now below the horizon radius of supermassive black holes viz.…”