부산대학교 도서관

The measurement of the cross-correlation function is crucial to assess magnification bias in galaxy surveys. Previous works used mini-tile subsampling, but accurately determining the integral constraint (IC) correction for unbiased estimation is challenging due to various factors. We present a new methodology for estimating the cross-correlation function, utilizing full field area and reducing statistical uncertainty. Covariance matrices were estimated by dividing each field into at least five patches using a k-mean clustering algorithm. Robustness was assessed by comparing spectroscopic and photometric lens samples, yielding compatible results. Cross-correlation and auto-correlation analyses in the GAMA fields revealed a stronger signal in GAMA15, likely due to rare large-scale structure combinations. Our findings highlight the robustness of the new methodology and suggest sample-specific effects. Subsequent papers in this series will explore other aspects of magnification bias and address potential biases from the GAMA15 signal on cosmological parameter constraints.
Comment: This work contains the methodological details of the magnification bias cross-correlation function (It is the first of a series of three) . 14 pages, 9 figures