2023-10-20 Abstract
Title: On the flexion measurement in weak lensing
Speaker: Prof. Toshifumi Futamase (Kyoto Sangyo U.)
Date: October 20 at 14:30
Location: R521, General Building II
Abstract:
It is expected that the high quality data taken by new generation of observational instruments such as JWST , EUCLID will tell us about the detailed properties of the dark matter and dark energy. However, these data far surpass previous data not only in its quantity but also in its quality, and this means that more accurate theoretical treatment will be required to get the scientific information out of these data. We develop such a treatment in weak lensing study. The weak lensing is known as the best method to study dark matter and dark anergy. The traditional method measures the gravitational shear of the lensing object which is the second derivatives of the lensing potential by observing essentially quadrupole moment of the shape of the background galaxies. However, for example, JWST data contains many faint and irregular small galaxies which are not directly used in the traditional method. We have developed a weak lensing method using the octupole moments of galaxy shape which give information of the third derivatives of the lensing potential (called flexion) and thus reveals more detailed mass distribution of the lensing object. In this talk I will give briefly an introduction of weak lensing. Then I explain our new method and demonstrate mass reconstruction by flexion for a cluster data taken by JWST.