MORPHOLOGIES OF ∼190,000 GALAXIES AT z = 0–10 REVEALED WITH HST LEGACY DATA. I. SIZE EVOLUTION

Abstract

We present the redshift evolution of the galaxy effective radius r e obtained from the Hubble Space Telescope ( HST ) samples of ∼190,000 galaxies at z = 0–10. Our HST samples consist of 176,152 photo- z galaxies at z = 0–6 from the 3D- HST +CANDELS catalog and 10,454 Lyman break galaxies (LBGs) at z = 4–10 identified in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), HUDF 09/12, and HFF parallel fields, providing the largest data set to date for galaxy size evolution studies. We derive r e with the same technique over the wide redshift range of z = 0–10, evaluating the optical-to-UV morphological K correction and the selection bias of photo- z galaxies+LBGs as well as the cosmological surface-brightness dimming effect. We find that r e values at a given luminosity significantly decrease toward high z , regardless of statistics choices (e.g., for median). For star-forming galaxies, there is no evolution of the power-law slope of the size–luminosity relation and the median Sérsic index ( ). Moreover, the r e distribution is well represented by log-normal functions whose standard deviation does not show significant evolution within the range of . We calculate the stellar-to-halo size ratio from our r e measurements and the dark-matter halo masses estimated from the abundance-matching study, and we obtain a nearly constant value of at z = 0–8. The combination of the r e -distribution shape+standard deviation, the constant , and suggests a picture in which typical high- z star-forming galaxies have disk-like stellar components in a sense of dynamics and morphology over cosmic time of . If high- z star-forming galaxies are truly dominated by disks, the value and the disk-formation model indicate that the specific angular momentum of the disk normalized by the host halo is . These are statistical results for major stellar components of galaxies, and the detailed study of clumpy subcomponents is presented in the paper II.