Abstract
ABSTRACT The DMASS sample is a photometric sample from the DES Year 1 data set designed to replicate the properties of the CMASS sample from BOSS, in support of a joint analysis of DES and BOSS beyond the small overlapping area. In this paper, we present the measurement of galaxy–galaxy lensing using the DMASS sample as gravitational lenses in the DES Y1 imaging data. We test a number of potential systematics that can bias the galaxy–galaxy lensing signal, including those from shear estimation, photometric redshifts, and observing conditions. After careful systematic tests, we obtain a highly significant detection of the galaxy–galaxy lensing signal, with total S/N = 25.7. With the measured signal, we assess the feasibility of using DMASS as gravitational lenses equivalent to CMASS, by estimating the galaxy-matter cross-correlation coefficient rcc. By jointly fitting the galaxy–galaxy lensing measurement with the galaxy clustering measurement from CMASS, we obtain $r_{\rm cc}=1.09^{+0.12}_{-0.11}$ for the scale cut of $4 \, h^{-1}{\rm \,\,Mpc}$ and $r_{\rm cc}=1.06^{+0.13}_{-0.12}$ for $12 \, h^{-1}{\rm \,\,Mpc}$ in fixed cosmology. By adding the angular galaxy clustering of DMASS, we obtain rcc = 1.06 ± 0.10 for the scale cut of $4 \, h^{-1}{\rm \,\,Mpc}$ and rcc = 1.03 ± 0.11 for $12 \, h^{-1}{\rm \,\,Mpc}$. The resulting values of rcc indicate that the lensing signal of DMASS is statistically consistent with the one that would have been measured if CMASS had populated the DES region within the given statistical uncertainty. The measurement of galaxy–galaxy lensing presented in this paper will serve as part of the data vector for the forthcoming cosmology analysis in preparation.
Highlights
Galaxies are biased density tracers as they form at the peaks of the matter density field (Kaiser 1984)
5 RESULTS we present the details of our measurement of galaxy-galaxy lensing and the cross-correlation coefficient rcc with the discussion about the implication of the results
We obtained rcc = 1.09+−00..1121 for the scale cut of 4h−1 Mpc and rcc = 1.06+−00..1132 for 12h−1 Mpc, both are consistent with the ideal value of rcc = 1 within 1σ
Summary
Galaxies are biased density tracers as they form at the peaks of the matter density field (Kaiser 1984). Several studies (Miyatake et al 2015; More et al 2015; Alam et al 2017a; Singh et al 2020; Amon et al 2018; Jullo et al 2019) have conducted a joint analysis of galaxy clustering and weak lensing using the BOSS galaxies as gravitational lenses on the deep imaging data from modern experiments, such as the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS; Heymans et al 2012) and Kilo-Degree Survey (KiDS; de Jong et al 2013). The value of rcc equal to one implies that the galaxy-galaxy lensing signal of DMASS on large scales where the linear theory is valid can be considered as being statistically consistent with the one that would have been measured if CMASS populated the full DES region. This is because the measurement of CMASS galaxy clustering (Chuang et al 2017) used in this work is consistent with the Planck 2018 cosmology, and the quantity rcc depends on the relative difference in the amplitude of galaxy clustering and galaxygalaxy lensing
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