Morphologies of ∼190,000 Galaxies at z = 0–10 Revealed with HST Legacy Data. III. Continuum Profile and Size Evolution of Lyα Emitters

Abstract

We present the redshift evolution of the radial surface brightness profile of the rest-frame UV and optical stellar continua for 9119 Ly α emitters (LAEs) at z  ≃ 0–8 and 0–2, respectively. Using Hubble Space Telescope data and the LAE catalogs taken from the literature, we derive the structural quantities of the 9119 LAEs, and of ≃180,000 of photo- z star-forming galaxies (SFGs) and Lyman break galaxies (LBGs) for comparison, by the well-tested profile fitting. From 936 well-fitted LAEs, we carefully define a homogeneous sample of LAEs falling in the same ranges of UV-continuum luminosity and Ly α equivalent width over z  ≃ 0–8, and evaluate the redshift evolution. We find that the distribution of effective radius r e is represented by a log-normal function, and that the median Sérsic index is almost constant at n  ≃ 1–1.5 for the LAEs over z  ≃ 0–7, suggesting that typical LAEs have a stellar-disk morphology. The size–luminosity relation of the LAEs decreases monotonically toward high z , following size–luminosity relations of SFGs and LBGs. The median r e values of the LAEs evolve significantly as r e  ∝ (1 + z ) −1.37 , similar to those of the SFGs and LBGs in the same luminosity range, in contrast with the claims of no evolution made by previous studies, whose LAE samples are probably biased to faint sources at low z . The r e distribution, star formation rate surface densities, and stellar-to-halo size ratios of the LAEs are comparable with those of the SFGs and LBGs, indicating that LAEs have stellar components similar to SFGs and LBGs with a Ly α emissivity controlled by non-stellar physics such as the geometry, kinematics, and ionization states of the interstellar/circumgalactic medium.