In this thesis, using general relativity, the null geodesics and black hole shadow of a spherically symmetric configuration of a black hole (surrounded by a dark matter shell) are studied. First, the standard
results of the photon sphere of Schwarzschild de-Sitter black hole is revisited and analyzed more carefully. Secondly, using an ansatz (piecewise metric function) commonly used in the literature to describe the mass distribution of the spherically symmetric black hole - dark matter configuration, the null geodesics through vacuum and dark matter are analyzed. Assuming an observer located at a finite distance from the black hole outside the dark matter shell, the black hole shadow angle is calculated exactly. Next, the mass of the dark matter shell is constrained numerically using the metric function and the photon spheres. These constraints are then used to show the dependence of the black hole shadow angle on the dark matter mass and on the observer distance.
School of Sciences and Engineering
MS in Physics
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(2022).Shadows of a Schwarzschild Black Hole Surrounded by a Spherically Symmetric Dark Matter [Master's Thesis, the American University in Cairo]. AUC Knowledge Fountain.
Ibrahim, Ahmad. Shadows of a Schwarzschild Black Hole Surrounded by a Spherically Symmetric Dark Matter. 2022. American University in Cairo, Master's Thesis. AUC Knowledge Fountain.