Title: Recent Progress in Weak Lensing Measurement

　　Location: Lecture Hall (third floor of Astronomy Building)

　　Date & Time: 3 PM, Oct 27 (Thursday)

　　Speaker: Prof. Jun Zhang (张骏)，Shanghai Jiao Tong University

　　Abstract: Weak lensing is an important probe of the cosmic structure and the scale evolution of our Universe. We show that the weak lensing effect (also called cosmic shear) can be measured accurately from background galaxy images through Fourier transformation in the presence of background noise, source Poisson noise, and finite pixel size, without assumptions on the morphologies of galaxy and PSF. More recently, we have further optimized the way of taking the ensemble average of the cosmic shear signal, and the way of measuring the point-spread-function at the positions of the galaxies. We show some preliminary measurement results usi说明: http://10.0.9.105/wcm/app/editor/editor/images/spacer.gifng the CFHTlens data, and demonstrate that our method is the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.