Open AccessMeasuring the cosmic shear in Fourier space
Author(s) -
Zhang Jun
Publication year - 2008
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.12585.x
Subject(s) - physics , galaxy , surface brightness , point spread function , astrophysics , surface brightness fluctuation , fourier transform , cosmic cancer database , satellite galaxy , interacting galaxy , astronomy , galaxy formation and evolution , optics , quantum mechanics
We propose to measure the weak cosmic shear using the spatial derivatives of the galaxy surface brightness field. The measurement should be carried out in Fourier space, in which the point spread function (PSF) can be transformed to a desired form with multiplications, and the spatial derivatives can be easily measured. This method is mathematically well defined regardless of the galaxy morphology and the form of the PSF, and involves simple procedures of image processing. Furthermore, with high‐resolution galaxy images, this approach allows one to probe the shape distortions of galaxy substructures, which can potentially provide much more independent shear measurements than the ellipticities of the whole galaxy. We demonstrate the efficiency of this method using computer‐generated mock galaxy images.