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 and 478 field galaxies with log(M-*/M-circle dot) >= 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 (r(1/2, maj)) from CANDELS Hubble Space Telescope (HST)/ F160W imaging. We find consistent mass-normalized (log(M-*/M-circle dot) = 10.7) sizes for quiescent field galaxies (r(1/2, maj) = 1.81 +/- 0.29 kpc) and quiescent cluster galaxies (r(1/2, maj) = 2.17 +/- 0.63 kpc). The mass-normalized size of star-forming cluster galaxies (r(1/2, maj) = 4.00 +/- 0.26 kpc) is 12% larger (Kolmogorov-Smirnov (KS) test 2.1 sigma) than star-forming field galaxies (r(1/2, maj) = 3.57 +/- 0.10 kpc). From the mass-color relation we find that quiescent field galaxies with 9.7 < log(M-*/M-circle dot) <= 10.4 are slightly redder (KS test 3.6 sigma) than quiescent cluster galaxies, while cluster and field quiescent galaxies with log(M-*/M-circle dot) > 10.4 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-*/M-circle dot) > 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 similar to 2.