Cosmologie

Accelerating Bayesian inference for cosmological pipelines

Summary

The proposed thesis aims to develop and apply a probabilistic programming language written in JAX and using SPMD parallelism on GPUs to scale Bayesian inference tasks on large cosmological datasets. This language has no equivalent on the market and will be a major asset for the scientific community. The thesis will require the development of low-level code and will be led collaboratively following the open-source philosophy.

Modélisation instrumentale, calibration et exploitation des données d’observation de la polarisation du CMB avec le Simons Observatory, dans le cadre du projet européen SciPol (H/F)

Contexte. L'une des principales questions de la cosmologie et de la physique modernes concerne l'origine de l'Univers tel que nous le connaissons aujourd'hui. Grâce aux progrès considérables réalisés au cours de la dernière décennie, en grande partie sous l'impulsion du satellite Planck dirigé par l'Europe, le décor est planté pour commencer à aborder cette question de manière formelle et précise.

Twisting of galaxy orientations and the intrinsic alignment of galaxies

The majority of galaxies appear to be elliptical when projected on the sky. Observations have shown that the shapes of these galaxies align with the tidal matter density field within which they are formed. Therefore the observation of the alignment of galaxies may provide information on this underlying tidal matter density field.

Inflationary non-Gaussianities in the CMB and large-scale structure

Inflation is an important theory of the primordial universe that explains amongst other things the origin of the fluctuations observed in the cosmic microwave background (CMB) and of the large-scale structure of the galaxy distribution. However, there are many different inflation models and one of the challenges of modern cosmology is to find ways to distinguish these models at the level of their predictions for observables, in order to confront them with experimental data.

Galaxy evolution in cluster and proto-clusters at z>1.5

One of the major challenges in the field of galaxy formation and evolution is to understand how early-type galaxy (ETG) star formation is quenched in the first epoch of their assembly. At present, deep space
imaging and spectroscopy observations give us the opportunity to answer this question as never before.

Cosmology dependence on the covariance of galaxy clusters in Rubin/LSST

The covariance of galaxy clusters is an important element when constraining cosmology with galaxy clusters. However its computation is costly in computational resources, especially when it depends on cosmology. We propose an evaluation of the impact on the cosmological parameters when the modeling of the cluster covariance is simplified. This is one of the projects for the preparation of the LSST-DESC cluster cosmology framework.
Cosmologie