Speaker
Description
Abstract
Gravitational lensing has become one of the most powerful probes of both astrophysics and cosmology,providing insights into dark matter, cosmic structure formation, and the accelerated expansion of the6 Universe. While the deflection of light by matter is well established within General Relativity, the role of the cosmological constant (Λ) in lensing remains debated (M. Ishak & W. Rindler 2010a; M. Sereno 2020). In this work, we revisit the effect of Λ on gravitational lensing within the standard ΛCDM framework, employing a simplified refractive-index formulation of the Schwarzschild–de Sitter metric. We derive a modified lens equation incorporating both matter and Λ contributions, showing that Λ induces a systematic reduction in the bending angle. Applying this formalism to Einstein ring systems from the CASTLES survey, we find that the Λ correction contributes at the ≈ 2% level—comparable to current measurement uncertainties but significant for high-precision lensing cosmology. Our results, consistent with previous theoretical studies (M. Bartelmann 2010; M. Oguri 2019), highlight that even small Λ-induced effects must be accounted for in the era of Euclid, LSST, and SKA, where percent-level precision in lensing measurements will be required.
| Stream | Science or Engineering |
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