Extragalactic Test of General Relativity from Strong Gravitational Lensing by using Artificial Neural Networks

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Auteurs principaux: Ran, Jing-Yu, Wei, Jun-Jie
Format: Preprint
Publié: 2023
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author Ran, Jing-Yu
Wei, Jun-Jie
author_facet Ran, Jing-Yu
Wei, Jun-Jie
contents This study aims to test the validity of general relativity (GR) on kiloparsec scales by employing a newly compiled galaxy-scale strong gravitational lensing (SGL) sample. We utilize the distance sum rule within the Friedmann-Lema\^ıtre-Robertson-Walker metric to obtain cosmology-independent constraints on both the parameterized post-Newtonian parameter $γ_{\rm PPN}$ and the spatial curvature $Ω_{k}$, which overcomes the circularity problem induced by the presumption of a cosmological model grounded in GR. To calibrate the distances in the SGL systems, we introduce a novel nonparametric approach, Artificial Neural Network (ANN), to reconstruct a smooth distance--redshift relation from the Pantheon+ sample of type Ia supernovae. Our results show that $γ_{\rm PPN}=1.16_{-0.12}^{+0.15}$ and $Ω_k=0.89_{-1.00}^{+1.97}$, indicating a spatially flat universe with the conservation of GR (i.e., $Ω_k=0$ and $γ_{\rm PPN}=1$) is basically supported within $1σ$ confidence level. Assuming a zero spatial curvature, we find $γ_{\rm PPN}=1.09_{-0.10}^{+0.11}$, representing an agreement with the prediction of 1 from GR to a 9.6\% precision. If we instead assume GR holds (i.e., $γ_{\rm PPN}=1$), the curvature parameter constraint can be further improved to be $Ω_k=0.11_{-0.47}^{+0.78}$. These resulting constraints demonstrate the effectiveness of our method in testing GR on galactic scales by combining observations of strong lensing and the distance--redshift relation reconstructed by ANN.
format Preprint
id arxiv_https___arxiv_org_abs_2309_11810
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Extragalactic Test of General Relativity from Strong Gravitational Lensing by using Artificial Neural Networks
Ran, Jing-Yu
Wei, Jun-Jie
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
This study aims to test the validity of general relativity (GR) on kiloparsec scales by employing a newly compiled galaxy-scale strong gravitational lensing (SGL) sample. We utilize the distance sum rule within the Friedmann-Lema\^ıtre-Robertson-Walker metric to obtain cosmology-independent constraints on both the parameterized post-Newtonian parameter $γ_{\rm PPN}$ and the spatial curvature $Ω_{k}$, which overcomes the circularity problem induced by the presumption of a cosmological model grounded in GR. To calibrate the distances in the SGL systems, we introduce a novel nonparametric approach, Artificial Neural Network (ANN), to reconstruct a smooth distance--redshift relation from the Pantheon+ sample of type Ia supernovae. Our results show that $γ_{\rm PPN}=1.16_{-0.12}^{+0.15}$ and $Ω_k=0.89_{-1.00}^{+1.97}$, indicating a spatially flat universe with the conservation of GR (i.e., $Ω_k=0$ and $γ_{\rm PPN}=1$) is basically supported within $1σ$ confidence level. Assuming a zero spatial curvature, we find $γ_{\rm PPN}=1.09_{-0.10}^{+0.11}$, representing an agreement with the prediction of 1 from GR to a 9.6\% precision. If we instead assume GR holds (i.e., $γ_{\rm PPN}=1$), the curvature parameter constraint can be further improved to be $Ω_k=0.11_{-0.47}^{+0.78}$. These resulting constraints demonstrate the effectiveness of our method in testing GR on galactic scales by combining observations of strong lensing and the distance--redshift relation reconstructed by ANN.
title Extragalactic Test of General Relativity from Strong Gravitational Lensing by using Artificial Neural Networks
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2309.11810