A composite Hubble Space Telescope image of massive galaxy cluster Abell 2744. 
Image credit: NASA/ESA/J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)


AMALGAM(( Stands for “Ajustement de Modèles Appliqué  aux Lentilles gravitationnelles dans les AMas de galaxies”, meaning “Lensing clusters through model fitting”)) is an observational cosmology project  supported by the French ANR and hosted by the IAP institute.

We propose to push forward the idea of a fast systematic model fitting of the light distribution of galaxies in wide field imaging data with a precise account for instrumental and observational effects. The goal is to perform high quality measurements of the shape of galaxies  which carries various levels of gravitational lensing signal.

While improving the state-of-the-art Astromatic toolkit,  we pay particular attention to blind software and method validation by participating to worlwide  challenges (e.g. Great3, ARCLETS).

Besides those shear measurements (first order distorsions due to lensing), we are also exploring the possibility of measuring the flexion regime (next order order in distorsions) as well as a full treatment of the strong lensing regime in the vicinity of clusters of galaxies. With those techniques in hand, we propose to shed light on the dark matter content in galaxy clusters on various scales.

Our project is based on the analysis of archival wide-field imaging data of more than 90 massive clusters of galaxies observed with the SUBARU and CFHT telescopes. The data were obtained through the SMOKA science archive and the CFHT science archive.


Lensing clusters through model fitting