The Wavelength Dependence of High-Redshift Galaxy Structure in the Rest-Frame Ultraviolet

Abstract

We present the rest-frame UV wavelength dependence of the Petrosian-like half-light radius ($r_{50}$), and the concentration parameter for a sample of 198 star-forming galaxies at 0.5 < z < 1.5. We find a ~5% decrease in $r_{50}$ from 1500 Å to 3000 Å, with half-light radii at 3000 Å ranging from 0.6 kpc to 6 kpc. We also find a decrease in concentration of ~0.07 (1.9 < $C_{3000}$ < 3.9). The lack of a strong relationship between $r_{50}$ and wavelength is consistent with a model in which clumpy star formation is distributed over length scales comparable to the galaxy's rest-frame optical light. While the wavelength dependence of $r_{50}$ is independent of size at all redshifts, concentration decreases more sharply in the far-UV (~1500 Å) for large galaxies at z ~ 1. This decrease in concentration is caused by a flattening of the inner ~20% of the light profile in disk-like galaxies, indicating that the central regions have different UV colors than the rest of the galaxy. We interpret this as a bulge component with older stellar populations and/or more dust. The size-dependent decrease in concentration is less dramatic at z ~ 2, suggesting that bulges are less dusty, younger, and/or less massive than the rest of the galaxy at higher redshifts.

11 pages, 9 figures, accepted to ApJ

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• Constraints on Quenching of $z\lesssim 2$ Massive Galaxies from the Evolution of the average Sizes of Star-Forming and Quenched Populations in COSMOS
• A Southern sky search for repeating Fast Radio Bursts using the Australian SKA Pathfinder
• Galaxies of the $z\sim 2$ Universe. I. Grism-Selected Rest-Frame Optical Emission Line Galaxies
• A new fitting concept for the robust determination of Sérsic model parameters
• Spitzer's View of the Candidate Cluster and Protocluster Catalog (CCPC)
• UV bright red-sequence galaxies: a comparative study between UV upturn and UV weak systems