THE EVOLUTION OF MASS-SIZE RELATION FOR LYMAN BREAK GALAXIES FROM <i>z</i> = 1 to <i>z</i> = 7

Abstract

For the first time, we study the evolution of the stellar mass-size relation for star-forming galaxies from z ∼ 4 to z ∼ 7 from Hubble-WFC3/IR camera observations of the HUDF and Early Release Science field. The sizes are measured by determining the best-fit model to galaxy images in the rest-frame 2100 Å with the stellar masses estimated from spectral energy distribution fitting to rest-frame optical (from Spitzer/IRAC) and UV fluxes. We show that the stellar mass-size relation of Lyman break galaxies (LBGs) persists, at least to z ∼ 5, and the median size of LBGs at a given stellar mass increases toward lower redshifts. For galaxies with stellar masses of 9.5 &lt; log (M */M ⊙) &lt; 10.4, sizes evolve as (1 + z)-1.20 ± 0.11. This evolution is very similar for galaxies with lower stellar masses of 8.6 &lt; log (M */M ⊙) &lt; 9.5 which is re ∝ (1 + z) -1.18 ± 0.10, in agreement with simple theoretical galaxy formation models at high z. Our results are consistent with previous measurements of the LBGs mass-size relation at lower redshifts (z ∼ 1-3). © © 2012. The American Astronomical Society. All rights reserved.