We present an independent calibration of the photometric redshift (photo-$z$) distributions for source galaxies in the Hyper Suprime-Cam year 3 (HSC Y3) weak lensing survey using small-scale galaxy-galaxy lensing. By measuring the tangential shear around spectroscopic lens galaxies from Galaxy and Mass Assembly, Sloan Digital Sky Survey, and Dark Energy Spectroscopic Instrument (DESI), divided into 15 narrow redshift bins, we compute shear ratios that are sensitive to the mean redshift of source galaxies. Using a blinded analysis, we derive constraints on the photo-$z$ bias parameters in source bins 2, 3, and 4, achieving signal-to-noise ratios of 59, 75, and 62, respectively. Our constraints for $\mathrm{\Delta }{z}_2$, $\mathrm{\Delta }{z}_3$, and $\mathrm{\Delta }{z}_4$ are consistent with those from HSC Y3 cosmic shear modeling. We observe a mild shift in the $\mathrm{\Delta }{z}_3\text{−}\mathrm{\Delta }{z}_4$ plane due to the heterogeneous depth of the lens sample, which disappears when using only DESI Data Release 1 lenses. Combining shear-ratio measurements with cosmic shear data, we obtain joint constraints on cosmological parameters: ${\mathrm{\Omega }}_{\mathrm{m}}=0.304_{-0.029}^{+0.03}$ and $S_8=0.773_{-0.031}^{+0.031}$, consistent with cosmic shear-only results. This work demonstrates the utility of small-scale lensing as an independent probe for calibrating photometric redshift bias in weak lensing cosmology.

Close

PrevNext

View figure in article

• Cosmological parameters
• Large scale structure of the Universe