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Probing the Universe with Cluster Gravitational Lensing: Status and Challenges| title | Probing the Universe with Cluster Gravitational Lensing: Status and Challenges |
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| start_date | 2025/05/06 |
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| schedule | 14h-16h |
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| online | no |
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| location_info | Amphi Yvonne Choquet-Bruhat |
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| summary | Cosmology is the study of the Universe: its composition, its large-scale structure, and its evolution. A key challenge is that most of the matter in the Universe is dark and invisible to direct observation. To map its distribution, we rely on indirect methods, and in particular on gravitational lensing, which exploits the deflection of light by the gravitational potential of massive structures. Observationally, lensing manifests as distortions in the shapes of background galaxies, and in extreme cases, the formation of multiple images of the same source. However, inferring the matter distribution from lensing observables is a complex inverse problem, requiring carefully designed modeling techniques. In this talk, I will review the steps involved in going from astrophysical images to mass maps, focusing on the largest gravitationally bound structures in the Universe: galaxy clusters. I will highlight several critical challenges where further methodological developments are ongoing. For instance, at the observational level, accurately measuring the shapes and positions of faint background galaxies remains difficult, particularly in images affected by atmospheric distortions, instrumental effects, and shot noise, issues that must be addressed to achieve the precision required for upcoming large surveys. I will also present our Bayesian mass reconstruction method, which combines a parametric model for the cluster-scale mass distribution with a flexible grid-based component to capture complex substructures. |
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| responsibles | Leclaire |
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Workflow history| from state (1) | to state | comment | date |
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| submitted | published | | 2025/04/29 12:23 UTC |
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