Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam
  first-year data
  We measure cosmic weak lensing shear power spectra with the Subaru Hyper
Suprime-Cam (HSC) survey first-year shear catalog covering 137deg$^2$ of the
sky. Thanks to the high effective galaxy number density of $\sim$17
arcmin$^{-2}$ even after conservative cuts such as magnitude cut of $i<24.5$
and photometric redshift cut of $0.3\leq z \leq 1.5$, we obtain a high
significance measurement of the cosmic shear power spectra in 4 tomographic
redshift bins, achieving a total signal-to-noise ratio of 16 in the multipole
range $300 \leq \ell \leq 1900$. We carefully account for various uncertainties
in our analysis including the intrinsic alignment of galaxies, scatters and
biases in photometric redshifts, residual uncertainties in the shear
measurement, and modeling of the matter power spectrum. The accuracy of our
power spectrum measurement method as well as our analytic model of the
covariance matrix are tested against realistic mock shear catalogs. For a flat
$\Lambda$ cold dark matter ($\Lambda$CDM) model, we find $S_8\equiv
\sigma_8(\Omega_{\rm m}/0.3)^\alpha=0.800^{+0.029}_{-0.028}$ for $\alpha=0.45$
($S_8=0.780^{+0.030}_{-0.033}$ for $\alpha=0.5$) from our HSC tomographic
cosmic shear analysis alone. In comparison with Planck cosmic microwave
background constraints, our results prefer slightly lower values of $S_8$,
although metrics such as the Bayesian evidence ratio test do not show
significant evidence for discordance between these results. We study the effect
of possible additional systematic errors that are unaccounted in our fiducial
cosmic shear analysis, and find that they can shift the best-fit values of
$S_8$ by up to $\sim 0.6\sigma$ in both directions. The full HSC survey data
will contain several times more area, and will lead to significantly improved
cosmological constraints.
