Hyper Suprime-Cam Year 3 results: Cosmology from galaxy clustering and weak lensing with HSC and SDSS using the emulator based halo model

Abstract

We present cosmology results from a blinded joint analysis of cosmic shear, ζ±, galaxy-galaxy weak lensing, Δς(R), and projected galaxy clustering, wp(R), measured from the Hyper Suprime-Cam three-year (HSC-Y3) shape catalog and the Sloan Digital Sky Survey (SDSS) DR11 spectroscopic galaxy catalog - a 3×2 pt cosmology analysis. We define luminosity-cut, and therefore nearly volume-limited, samples of SDSS galaxies to serve as the tracers of wp and as the lens samples for Δς in three spectroscopic redshift bins spanning the range 0.15<z<0.7. For the ζ± and Δς measurements, we use a single sample of about seven million source galaxies over 416 deg2, selected from HSC-Y3 based on having photometric redshifts (photo-z) greater than 0.75. The deep, high-quality HSC-Y3 data enable significant detections of the Δς signals, with integrated signal-to-noise ratio S/N∼24 in the range 3≤R/[h-1 Mpc]≤30 over the three lens samples. ζ± has S/N∼19 in the range 8′≤ ≤50′ and 30′≤ ≤150′ for ζ+ and ζ-, respectively. For cosmological parameter inference, we use the dark emulator package, combined with a halo occupation distribution prescription for the relation between galaxies and halos, to model wp and Δς down to quasinonlinear scales, and we estimate cosmological parameters after marginalizing over nuisance parameters. In our baseline analysis we employ an uninformative flat prior of the residual photo-z error, given by Π(Δzph)=U(-1,1), to model a residual bias in the mean redshift of HSC source galaxies. Comparing the relative lensing amplitudes for Δς in the three redshift bins and for ζ± with the single HSC source galaxy sample allows us to calibrate the photo-z parameter Δzph to the precision of σ(Δzph)≃0.09. With these methods, we obtain a robust constraint on the cosmological parameters for the flat ΛCDM model: S8=σ8(ωm/0.3)0.5=0.763-0.036+0.040, or the best-constrained parameter given by S8′=σ8(ωm/0.3)0.22=0.721±0.028, determined with about 4% fractional precision. Based on multidimensional tension metrics, HSC-Y3 data exhibits about 2.5σ tension with the cosmological constraint inferred by Planck for the ΛCDM model, and hints at a nonzero residual photo-z bias implying that the true mean redshift of the HSC galaxies at z≳0.75 is higher than that implied by the original photo-z estimates. © 2023 American Physical Society.