The Size Evolution of Star-forming Galaxies since z 7 Using ZFOURGE
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AbstractFor the first time, we present the size evolution of a mass-complete (log(M*/M)>10) sample of star-forming galaxies over redshifts z=17, selected from the FourStar Galaxy Evolution Survey. Observed H-band sizes are measured from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) Hubble Space Telescope (HST)/F160W imaging. Distributions of individual galaxy masses and sizes illustrate that a clear masssize relation exists up to z7. At z7, we find that the average galaxy size from the masssize relation is more compact at a fixed mass of log(M*/M)=10.1, with kpc, than at lower redshifts. This is consistent with our results from stacking the same CANDELS HST/F160W imaging, when we correct for galaxy position angle alignment. We find that the size evolution of star-forming galaxies is well fit by a power law of the form kpc, which is consistent with previous works for normal star-formers at 1<z<4. In order to compare our slope with those derived Lyman break galaxy studies, we correct for different IMFs and methodology and find a slope of 0.970.02, which is shallower than that reported for the evolution of Lyman break galaxies (LBGs) at z>4 (). Therefore, we conclude the LBGs likely represent a subset of highly star-forming galaxies that exhibit rapid size growth at z>4.
