Cosmologie

Dans le cadre de la préparation des données du télescope LSST de l’observatoire Vera C. Rubin qui fear sa première lumière en 2025, l’un des défis majeurs est le deblending des galaxies, c’est-à-dire la séparation des contributions lumineuses de galaxies superposées dans les images astronomiques.

According to the standard cosmological model, about 95% of the Universe's energy content is in two unknown forms: dark energy, responsible for accelerating cosmic expansion, and dark matter, the predominant form of matter. Understanding these components is one of the key challenges in modern physics and cosmology.

During the last decade, cosmology has entered a precision era, leading to the prevalence of the standard cosmological model, ΛCDM. Nevertheless, the main ingredient of this model, the so-called dark energy, remains mysterious while dominating the energy budget of the Universe. Its comprehension is therefore one of the main goals in this domain.

Observations of the Cosmic Microwave Background fluctuations provide a unique view onto the early Universe and the fundamental laws of physics at the most extreme energies (typically twelve orders of magnitude above what could be achieved at the Large Hadron Collider). The successful European-led space mission Planck provided the ultimate characterization of the CMB fluctuations in total intensity and a robust detection of some of the polarization signal.

The quest for B-mode polarization of the Cosmic Microwave Background is the primary challenge in Observational Cosmology and is pursued by a worldwide effort. Measurement of B-mode polarization in the CMB will be clear evidence of primordial gravitational waves which are theoretically expected to be produced during inflation at about 10-35 seconds after the Planck epoch. Their presence would be a non-trivial result concerning quantum gravity because tensor modes would mean the metric must be quantized.

The student will participate in the development and exploitation of the parametric, map-based pipeline for the scientific exploitation of CMB polarization data sets from the Simons Observatory (SO). Although this pipeline is optimized for the detection of primordial B-modes, the intern will lead an effort to measure the performance of the SO Small Aperture Telescopes to detect and characterize E-modes. Beyond their usefulness for calibration and to detect potential systematic effects, E-modes on the largest angular scales could have an important impact on e.g.