Weak Lensing Mass Mapping and Cosmology Inference 2

Weak gravitational lensing, a subtle bending of light from distant galaxies by intervening mass, serves as a powerful probe into the dark sector of the universe, offering insights into the evolution of dark-matter structures, as well as helping distinguish between dark energy and models of modified gravity.

Team Members:

• Andreas Tersenov
• Jean-Luc Starck

Objectives
The objective of this project is to advance the field of cosmology by:

• Developing novel data-driven approaches for the robust reconstruction of weak-lensing mass maps across different redshift bins.
• Introducing and exploring novel higher-order statistics for the analysis of these maps.
• Using likelihood-based and likelihood-free inference methods to produce cosmology constraints from weak-lensing observations and test different models of cosmology.
• Applying the methods to data from contemporary surveys like CFHTLenS, HSC, DES, UNIONS, KiDS, and the recently launched Euclid mission.

Methodology: The project aims to develop a versatile analysis pipeline that processes a weak lensing catalog to get cosmology constraints, and encompasses the following key stages: Mass Mapping: Implementing a flexible framework that allows for the application of multiple mass mapping techniques to weak lensing catalogs. Higher-Order Statistics: Computing advanced statistics on the mass maps to extract information about the cosmic structure, including peak counts, wavelet peak counts, and the wavelet l1-norm. Simulation Comparison and Bayesian Inference: Leveraging a vast array of simulations to construct likelihood functions for Bayesian inference, enabling the derivation of cosmological parameters and testing different models of cosmology.

The first implementation of the pipeline will be to investigate the impact of different mass mapping methods on cosmological constraints, aiming to understand how the choice of mass mapping techniques affects the inferred cosmological parameters. Next, the pipeline will be applied to real observational data from the UNIONS survey, aiming to obtain new observational constraints on cosmological parameters.