Weak Gravitational Lensing: A Brief Overview

Fuente: arXiv
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Main Authors: Basumallick, Partha Pratim, Das, Saheb, Mandal, Bhaswati, Sau, Subhadip
Format: Preprint
Published: 2026
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author Basumallick, Partha Pratim
Das, Saheb
Mandal, Bhaswati
Sau, Subhadip
author_facet Basumallick, Partha Pratim
Das, Saheb
Mandal, Bhaswati
Sau, Subhadip
contents Gravitational lensing constitutes one of the most direct observational manifestations of spacetime curvature and provides a powerful probe of compact astrophysical objects. In this work, we present a comprehensive analysis of the bending of light in curved spacetime, beginning with the fundamental aspects of gravitational lensing and the Newtonian approximation to light deflection. The relativistic formulation of lensing is then developed through the lens equation, lensing potential, and a geometrical interpretation of Fermat's principle using an effective refractive index in curved spacetime. Photon trajectories and light deflection are subsequently investigated in static, spherically symmetric geometries, followed by a detailed study of photon motion in the equatorial plane of the Kerr spacetime. Analytical expressions for the closest approach distance and critical parameters governing photon orbits are derived. Furthermore, the bending angle is examined using the Rindler-Ishak method and the Gauss-Bonnet theorem within the optical geometry. Finally, the analysis is extended to axisymmetric spacetimes using the OIA and GW-OIA formalisms, providing a unified geometrical framework for computing light deflection in both static and rotating gravitational fields.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17355
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Weak Gravitational Lensing: A Brief Overview
Basumallick, Partha Pratim
Das, Saheb
Mandal, Bhaswati
Sau, Subhadip
General Relativity and Quantum Cosmology
Gravitational lensing constitutes one of the most direct observational manifestations of spacetime curvature and provides a powerful probe of compact astrophysical objects. In this work, we present a comprehensive analysis of the bending of light in curved spacetime, beginning with the fundamental aspects of gravitational lensing and the Newtonian approximation to light deflection. The relativistic formulation of lensing is then developed through the lens equation, lensing potential, and a geometrical interpretation of Fermat's principle using an effective refractive index in curved spacetime. Photon trajectories and light deflection are subsequently investigated in static, spherically symmetric geometries, followed by a detailed study of photon motion in the equatorial plane of the Kerr spacetime. Analytical expressions for the closest approach distance and critical parameters governing photon orbits are derived. Furthermore, the bending angle is examined using the Rindler-Ishak method and the Gauss-Bonnet theorem within the optical geometry. Finally, the analysis is extended to axisymmetric spacetimes using the OIA and GW-OIA formalisms, providing a unified geometrical framework for computing light deflection in both static and rotating gravitational fields.
title Weak Gravitational Lensing: A Brief Overview
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2604.17355