Tesis Magíster

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Browsing Tesis Magíster by Author "Agurto Sepúlveda, Felipe Eduardo"

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    Exploring how deviations from the Kerr metric affect images of supermassive black holes.
    (Universidad de Concepción., 2023) Agurto Sepúlveda, Felipe Eduardo; Schleicher, Dominik
    The description of black holes (BH) according to General Relativity (GR), particularly through the Kerr solution, is based on simplified assumptions. In this context, we investigate the impact of deviations from the Kerr solution on images of supermassive black holes (SMBHs). We utilize simulations of General Relativistic Radiative Transport, focusing on the Kerr-Like metric, which features four non-linear functions of free deviation, is stationary, axisymmetric, and asymptotically flat. Additionally, we explore two metrics of modified gravity: the Chern-Simons theory and the α′-corrected theory, both derived as low-energy limits of string theory. To obtain images, we employ the RAPTOR I code, an open-source ray-tracing tool that supports diverse spacetime geometries. We quantify deviations by studying the asymmetry, diameter, and displacement of the BH shadow, comparing them with a Kerr BH. Our results validate the effectiveness of the developed method for measuring deviations and show that these affect the shape of the shadow, with the deviations A1(r) and A2(r) of the Kerr-Like metric being particularly relevant. However, we observe that the distribution of matter and emissivities around the black hole also play a role. Thus, the geometry and effects of deviations on the shadow cannot be solely predicted from the shape of the photon ring. Furthermore, we demonstrate that deviations arising from modified gravity theories, especially the effective limit of Chern-Simons gravity, are imperceptible in black hole images. Likewise, we present the separability of the slowly-rotating black hole solution in the α′-corrected theory within the Hamilton-Jacobi equations, which promotes future studies of its shadow.
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