THE DIFFERENTIAL SIZE GROWTH OF FIELD AND CLUSTER GALAXIES AT z = 2.1 USING THE ZFOURGE SURVEY
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© 2015. The American Astronomical Society. All rights reserved. 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∗/) ≥ 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 () from CANDELS Hubble Space Telescope (HST)/F160W imaging. We find consistent mass-normalized (log(M∗/) = 10.7) sizes for quiescent field galaxies ( kpc) and quiescent cluster galaxies ( kpc). The mass-normalized size of star-forming cluster galaxies ( kpc) is 12% larger (Kolmogorov-Smirnov (KS) test ) than star-forming field galaxies ( kpc). From the mass-color relation we find that quiescent field galaxies with 9.7 < log(M∗/) are slightly redder (KS test 3.6σ) than quiescent cluster galaxies, while cluster and field quiescent galaxies with log(M∗/) > 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∗/) ; 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.
author list (cited authors)
Allen, R. J., Kacprzak, G. G., Spitler, L. R., Glazebrook, K., Labbé, I., Tran, K., ... Tomczak, A. R.