http://arxiv.org/abs/2002.09826
Galaxy intrinsic alignment (IA) is both a source of systematic contamination to cosmic shear measurement and its cosmological applications, and a source of valuable information on the large scale structure of the universe and galaxy formation. The self-calibration (SC) method \citep{SC2008} was designed to separate IA from cosmic shear, free of IA modeling. It was first successfully applied to the KiDS450 and KV450 data \citep{Yao2019}. We apply the SC method to the DECaLS DR3 shear + photo-z catalog and significantly improve the IA detection to $\sim 20\sigma$. We find a strong dependence of IA on galaxy color, with strong IA signal for red galaxies, and weak/vanishing IA signal for blue galaxies. The detected IA for red galaxies is in reasonable agreement with the non-linear tidal alignment model and the inferred IA amplitude increases with redshift. We discuss various caveats and possible improvements in the measurement, theory and parameter fitting that will be addressed in future works.
J. Yao, H. Shan, P. Zhang, et. al.
Tue, 25 Feb 20
55/76
Comments: Submitted to ApJ
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