ZFIRE: SIMILAR STELLAR GROWTH IN H alpha-EMITTING CLUSTER AND FIELD GALAXIES AT z similar to 2
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We compare galaxy scaling relations as a function of environment at z 2 with our ZFIRE survey12 where we have measured H fluxes for 90 star-forming galaxies selected from a mass-limited (log(Mz.astModot) > 9) sample based on ZFOURGE.13 The cluster galaxies (37) are part of a confirmed system at z=2.095 and the field galaxies (53) are at 1.9 < z < 2.4; all are in the COSMOS legacy field. There is no statistical difference between H- emitting cluster and field populations when comparing their star formation rate (SFR), stellar mass (M), galaxy size (reff ), SFR surface density ((H star)), and stellar age distributions. The only difference is that at fixed stellar mass, the H-emitting cluster galaxies are log(reff ) 0.1 larger than in the field. Approximately 19% of the H-emitters in the cluster and 26% in the field are IR-luminous (LIR > 2> 1011 L). Because the luminous IR galaxies in our combined sample are 5 times more massive than the low-IR galaxies, their radii are 70% larger. To track stellar growth, we separate galaxies into those that lie above, on, or below the H star-forming main sequence (SFMS) using SFR(M)=0.2 dex. Galaxies above the SFMS (starbursts) tend to have higher H SFR surface densities and younger light-weighted stellar ages than galaxies below the SFMS. Our results indicate that starbursts (+SFMS) in the cluster and field at z 2 are growing their stellar cores. Lastly, we compare to the (SFR-M) relation from RHAPSODY-G cluster simulations and find that the predicted slope is nominally consistent with the observations. However, the predicted cluster SFRs tend to be too low by a factor of 2, which seems to be a common problem for simulations across environment.
