Preparing Dark Energy Studies with Euclid: Simulating Images
Dark energy and dark matter are the great mysteries in cosmology today. Understanding the distribution of dark matter in the Universe and obtaining strong constraints on the nature of dark energy and its possible origins are the main goals of ESA’s dark energy mission Euclid.
Euclid will perform deep, high-resolution observations of a large fraction of the sky in the optical and infrared domains. The goal is to derive a three-dimensional map of the Universe to observe the influence of dark matter and dark energy. In order to do so, for each of the 1 billion galaxies detected by Euclid, not only their apparent position in the sky has to be measured, but also their distance, i.e., their redshift. Euclid data alone do not permit this measurement, so additional data from ground-based telescopes (e.g., from the Dark Energy Survey, the Large Synoptic Survey Telescope, and the Canada-France-Hawaii Telescope) must be used in combination with Euclid data.
The Euclid consortium is developing simulations of both Euclid and ground-based data to prepare their combined analysis. At APC we are responsible for simulating ground-based optical images, and are currently working on simulations of the Dark Energy Survey (DES), which is a survey performed at the 4-meter Blanco telescope in Chile. We take galaxies from cosmological simulations, adding stars from a Galactic model, and process them through the survey simulator to produce realistic DES images including effects such as atmospheric seeing and detector noise. These DES simulations will then be combined with Euclid data by the Euclid pipeline.
The object of the internship will be to characterize the DES simulations with the aim of comparing them to real data from DES. The student will learn about cosmological simulations and how to detect objects in astronomical images, measure their flux, size, color and shape using standard astronomical tools. He/She will use these measurements in statistical analyses to compare simulated and real images from DES. In the larger context, he/she will learn about dark matter/dark energy research and experiments, the Euclid mission in particular, and analysis of wide-field astronomical surveys. The internship will offer experience with how cosmologists tackle the challenge of studying dark energy and dark matter through observations. The student will workas a member of the Euclid team, establishing an excellent basis for a possible PhD project. A good understanding of Python and statistical analysis are recommended for this project. Experience with astronomical imaging data analysis and basic knowledge of cosmology are assets.
Contact: Cyrille Rosset, James Bartlett cyrille.rosset
apc.univ-paris7.fr, bartlettapc.univ-paris7.fr