The Size Evolution of Galaxies since z~3: Combining SDSS, GEMS, and FIRES
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo; van der Wel, Arjen; Rix, Hans-Walter; van der Werf, Paul; Toft, Sune; Trujillo, Ignacio; Förster Schreiber, Natascha M.; Barden, Marco; McIntosh, Daniel H.; Rudnick, Gregory; Moorwood, Alan; Röttgering, Huub; van Starkenburg, Lottie; Caldwell, J. A. R.; Zirm, Andrew; Häussler, Boris
Germany, United Kingdom, United States, Netherlands
Abstract
We present the evolution of the luminosity-size and stellar mass-size relations of luminous (LV>~3.4×1010 h-270 Lsolar) and massive (M*>~3×1010 h-270 Msolar) galaxies in the last ~11 Gyr. We use very deep near-infrared images of the Hubble Deep Field-South and the MS 1054-03 field in the Js, H, and Ks bands from FIRES to retrieve the sizes in the optical rest frame for galaxies with z>1. We combine our results with those from GEMS at 0.2<z<1 and SDSS at z~0.1 to achieve a comprehensive picture of the optical rest-frame size evolution from z=0 to 3. Galaxies are differentiated according to their light concentration using the Sérsic index n. For less concentrated objects, the galaxies at a given luminosity were typically ~3+/-0.5 (+/-2 σ) times smaller at z~2.5 than those we see today. The stellar mass-size relation has evolved less: the mean size at a given stellar mass was ~2+/-0.5 times smaller at z~2.5, evolving proportionally to (1+z)-0.40+/-0.06. Simple scaling relations between dark matter halos and baryons in a hierarchical cosmogony predict a stronger (although consistent within the error bars) than observed evolution of the stellar mass-size relation. The observed luminosity-size evolution out to z~2.5 matches well recent infall model predictions for Milky Way-type objects. For low-n galaxies, the evolution of the stellar mass-size relation would follow naturally if the individual galaxies grow inside out. For highly concentrated objects, the situation is as follows: at a given luminosity, these galaxies were ~2.7+/-1.1 times smaller at z~2.5 (or, put differently, were typically ~2.2+/-0.7 mag brighter at a given size than they are today), and at a given stellar mass the size has evolved proportionally to (1+z)-0.45+/-0.10.
Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO LP 164.O-0612). Also, based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.