THE DIFFERENTIAL SIZE GROWTH of FIELD and CLUSTER GALAXIES at z = 2.1 USING the ZFOURGE SURVEY

There is ongoing debate regarding the extent that environment affects galaxy size growth beyond z>1. To investigate the differences in star-forming and quiescent galaxy properties as a function of environment at z=2.1, we create a mass-complete sample of 59 cluster galaxies Spitler et al. (2012) and 478 field galaxies with log(M)>9 using photometric redshifts from the ZFOURGE survey. We compare the mass-size relation of field and cluster galaxies using measured galaxy semi-major axis half-light radii (r1/2,maj) from CANDELS HST/F160W imaging. We find consistent mass normalized (log(M)=10.7) sizes for quiescent field galaxies (r1/2,maj=1.81±0.29 kpc) and quiescent cluster galaxies (r1/2,maj=2.17±0.63 kpc). The mass normalized size of star-forming cluster galaxies (r1/2,maj=4.00±0.26 kpc ) is 12% larger (KS test 2.1σ) than star-forming field galaxies (r1/2,maj=3.57±0.10 kpc). From the mass-color relation we find that quiescent field galaxies with 9.710.4 have consistent colors. We find that star-forming cluster galaxies are on average 20% redder than star-forming field galaxies at all masses. Furthermore, we stack galaxy images to measure average radial color profiles as a function of mass. Negative color gradients are only present for massive star-forming field and cluster galaxies with log(M)>10.4, the remaining galaxy masses and types have flat profiles. Our results suggest given the observed differences in size and color of star-forming field and cluster galaxies, that the environment has begun to influence/accelerate their evolution. However, the lack of differences between field and cluster quiescent galaxies indicates that the environment has not begun to significantly influence their evolution at z~2.