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arXiv · 2501.15086

Model-Independent Probe of Cosmic Distance Duality Relation

Savita Gahlaut
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Abstract

In this paper, cosmic distance duality relation is probed without considering any background cosmological model. The only \textit{a priori} assumption is that the Universe is described by the Friedmann-Lema$\hat{i}$tre-Robertson-Walker (FLRW) metric The strong gravitational lensing (SGL) data is used to construct the dimensionless co-moving distance function $d(z)$ and latest type Ia supernovae (SNe Ia) Pantheon+ data is used to estimate luminosity distances at the corresponding redshifts $z$. Using the distance sum rule along null geodesics of the FLRW metric, the CDDR violation is probed in both flat and non-flat space-time by considering two parametrizations for $\eta(z)$, the function generally used to probe the possible deviations from CDDR. The results show that, CDDR is compatible with the observations at a very high level of confidence for linear parametrization in flat Universe. In non-flat Universe too, CDDR is valid within $1\sigma$ confidence interval with a mild dependence of $\eta$ on the curvature density parameter $\Omega_{K}$ . The results for non-linear parametrization also show no significant deviation from CDDR.

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Savita Gahlaut. 2025-01-25. Model-Independent Probe of Cosmic Distance Duality Relation. https://doi.org/10.1088/1674-4527/adae45

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