| 研究実績の概要 |
I analytically developed an improved version of the Fourier Power Function Shapelets (FPFS) algorithm for accurate and fast shear estimation. The method now includes analytic corrections for sources of bias that plague all shape measurement algorithms: including noise bias (due to noise in nonlinear combinations of observable quantities) and selection bias (due to sheared galaxies being more or less likely to be detected). Crucially, these analytic solutions do not rely on calibration from external image simulations. For isolated galaxies, the small residual less than 0.001 multiplicative bias and less than 0.0001 additive bias now meet science requirements for Stage IV experiments. FPFS also works accurately for faint galaxies and robustly against stellar contamination.
I conducted several systematic null tests for the HSC three-year cosmic shear measurement. One is to test the systematics in cosmic shear measurement caused by model residuals of point spread function due to diffraction of telescope and atmosphere. I cross-correlate galaxy shape with star shape to detect the PSF modelling residual in the galaxy shapes. The other null test is to check the B-mode systematics in the weak-lensing science. Then I looked into the influence of baryonic effect, the influence of the intrinsic alignment in the cosmic shear measurement. I have built up the analysis pipeline for HSC three year weak lensing cosmological constraints.
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