The Nature of Low-surface-brightness Galaxies in the Hyper Suprime-Cam Survey

We present the statistical redshift distribution of a large sample of low-surface-brightness (LSB) galaxies identified in the first 200 deg² of the Hyper Suprime-Cam Strategic Survey Program. Through cross-correlation with the NASA-SDSS Atlas, we find that the majority of objects lie within z < 0.15 or ~500 Mpc, yielding a mass range of M _* ≈ 10⁷-10⁹ M _⊙ and a size range of r _eff,g ≈ 1-8 kpc. We find a peak in the distance distribution within 100 Mpc, corresponding mostly to ~10⁷ M _⊙ galaxies that fall on the known mass-size relation. There is also a tail in the redshift distribution out to z ≈ 0.15, comprising more massive (M _* = 10⁸ - 10⁹ M _⊙) galaxies at the larger end of our size range. We see tentative evidence that at the higher-mass end (M _* > 10⁸ M _⊙), the LSB galaxies do not form a smooth extension of the mass-size relation of higher-surface-brightness galaxies, perhaps suggesting that the LSB galaxy population is distinct in its formation path.