STAGE Weak gravitational lensing: shear measurement and calibration in CFIS data

http://www.cosmostat.org/jobs



Nature du travail demandé : Simulations numériques,

Traitement de données



One of the most important techniques for cosmological analyses in modern surveys is weak gravitational lensing, which allows us to measure the total mass distribution (including dark matter) of the Universe from galaxy images. The quality of weak lensing measurements in observations depends on the accuracy of the ellipticity estimation of the galaxy images and its correct calibration.



This internship will consist on applying different calibration approaches on the images coming from the Canada-France Imaging Survey (http://cfht.hawaii.edu/en/science/LargePrograms/LP_17_19/index.php).

With 5,000 deg2 sky coverage this will be one of the largest weak-lensing surveys ever conducted. On one side, the student will apply the so-called metacalibration approach for CFIS data to produce a weak lensing catalogue which is independent on simulations. On the other side, the student will use a bias calibration based on machine learning techniques on CFIS image simulations that will be applied to the real data. We will compare the performance and consistencies of both methods and will also study the impact of this calibration on different statistics and cosmological analyses.