Missions

Our team has developed several algorithms for advanced decontamination of spectra produced by the Euclid satellite, based on 3 different approaches:
• Local approach with a non-convolutional model: sources are decontaminated one by one. The estimated spectrum of each source remains convolved with the LSF (Line Spread Function).
• Global approach with the non-convolutional model: a single algorithm allows to decontaminate all sources located in a predefined area. The estimated spectrum of each source remains convolved with the LSF.
• Local approach with the convolutional model: a source is decontaminated and deconvolved from the LSF at the same time.
The CDD's missions will be to implement, test and validate these 3 methods in the spectra processing chain provided by Euclid.

Activités

• The first task of the CDD will be to implement the global method with the non-convolutional model. This method, faster than the local method, requires the adjustment of several parameters. The CDD will have to carry out a comparative study in order to propose the optimal choice of these parameters.
• The second task will be to implement the local convolutional method which seems to be the most efficient according to preliminary tests. This method can be carried out with several algorithms each requiring the adjustment of several parameters. Additional studies will therefore be necessary before selecting the best algorithm and the best set of parameters.
• The CDD will also have to carry out a statistical study of these three methods using simulated data. This study will be essential to evaluate the effectiveness of these methods in different configurations.
• Finally, the CDD will have to test all the methods developed on real data when the latter becomes available. This step will make it possible to validate the effectiveness of the methods developed and adjust them if necessary.

Compétences

Skills in signal/image processing (in particular source separation and beamforming) and programming (Python and Matlab).

Contexte de travail

IRAP (Institute for Research in Astrophysics and Planetology) is the largest French laboratory where most areas of research in the sciences of the universe are addressed: from the solar system to cosmology, including stellar physics, exo-planets, star formation, high energy astrophysics, large-scale structures, galaxies and signal processing. IRAP is a major player in the development of space missions and instruments for the largest telescopes. The CDD will carry out its work in direct contact with researchers from the SISU (Signal-Image in Universe Sciences) and GAHEC (Galaxies, High Energy Astrophysics and Cosmology) groups involved in the Euclid mission. Euclid is an ESA (European Space Agency) space mission, launched in July 2023, whose main goal is to understand the accelerated expansion of the Universe. It will use two specific probes to investigate the nature of dark energy, dark matter and fundamental physics, using observational signatures capable of tracing the geometry of the Universe and the formation of structures. This is a massive “survey” type mission in imaging and spectroscopy. The CDD work will be carried out within the framework of processing the spectra provided by Euclid, which are “mixed” on the detectors due to instrumental constraints.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

One or two mission(s) in a European institute are possible over the duration of the contract.